Stephens, who is currently ranked 73rd in the world, having been number three on the WTA Tour in 2018, triumphed 6-7 (5-7) 7-5 6-1 over Watson in two hours, 50 minutes on Wednesday.
In a see-sawing match, there were six breaks in the opening set, as Watson got the edge early on Stephens' serve at the WTA Premier 1000 event.
Stephens steadied by claiming a late break in the second to level the match, before dominating the third set.
Playing at her 10th Indian Wells Open, Stephens won seven consecutive games after the match was 5-5 in the second set.
"After the first set, that was disappointing to lose that one, but I felt like it was a battle and I was still in the match," Stephens said. "I knew I had to keep fighting and that's what I did, and I'm just really pleased to have squeaked out a win here."
KEYS ON SONG IN OPENER
Former world number seven Madison Keys moved through to the second round with a 6-0 7-5 win over fast-finishing Estonian veteran Kaia Kanepi.
American Keys won 21 consecutive points as part of a streak where she clinched the first nine games of the match, withstanding Kenapi's late push.
Keys will take on Russian ninth seed Anastasia Pavlyuchenkova for a spot in the third round.
SAMSONOVA, MARTIC, ROGERS AND PUTINTSEVA PROGRESS
Liudmila Samsonova, who made the fourth round at Wimbledon earlier this year, needed more than two hours to get past Ukrainian qualifier Kateryna Kozlova 6-4 7-6 (8-6).
Samsonova will face countrywoman and 25th seed Veronika Kudermetova in the second round.
Petra Martic won through to take on second seed Iga Swiatek with a 6-4 6-4 victory over American wildcard Katie Volynets.
Ash Barty's US Open conqueror Shelby Rogers claimed her 25th win for the year, getting past Ukrainian Anhelina Kalinina 7-6 (7-2) 6-2, while Yulia Putintseva won 7-6 (7-2) 6-1 over experienced German Andrea Petkovic to set up a showdown with fellow Kazakh player and 13th seed Elena Rybakina.
Winning her 11th successive match, the Pole added to her triumph in Doha last month after prevailing in one hour and 20 minutes.
Swiatek subsequently climbed to a career-high second in the WTA rankings; making her the first Polish player to do so since Agnieszka Radwanska in July 2012.
The 20-year-old also claimed her fifth career title; becoming only the fifth woman to reach that tally before her 21st birthday after Kim Clijsters, Venus Williams, Serena Williams and Svetlana Kuznetsova.
"After playing so well in previous tournaments, I didn’t know it was possible for me to play that well for that long," said the former French Open champion, who claimed her second successive win over Sakkari having also prevailed in the Qatar Open semi-finals.
"I want to congratulate Maria. Every match against her is a great battle. I know that we've already started a cool rivalry.
"I think it's going to last for 10 more years, so it's going to be exciting, and I’m sure we're going to play many more finals.
"I want to thank my team; they're doing an amazing job calming me down and getting me to the place where I'm more confident and developing my tennis."
The two finalists struggled to settle during the opening set; both hitting five double-faults as six of the first seven games went against the serve.
But 12 unforced errors to her opponent's seven proved crucial for Sakkari, who had only been broken seven times in her five previous matches, as third seed Swiatek drew first blood after 45 minutes.
Losing only her second set of the week, sixth seed Sakkari had been beaten on all three occasions in 2022 when losing the opener.
Meanwhile, Swiatek had not dropped a set since her fourth-round victory over Angelique Kerber, and built on that momentum as she dominated the second.
The former Roland Garros champion broke her opponent twice more, as she only required an additional 35 minutes to wrap up victory; a sweeping forehand sealing the deal.
The Polish world number four came back from a break down in each set - as well as saving two set points in the first-set tiebreak - to level her head-to-head record with Halep at 2-2.
After taking out the WTA 1000 tournament in Doha last month, Swiatek has not had it all her way this week in California. Aside from a 6-1 6-0 trouncing of Madison Keys, the 20-year-old had to fight from a set down in her opening three matches.
Following a tight first set, Halep won three games in a row to take a 4-2 lead, but it was here Swiatek started to open up on return of serve.
She was ultimately able to capitalise on Halep's second serve, winning 14 of a total 21 points when given a second look, to earn five service breaks for the match.
Swiatek is now at least guaranteed to reach a career-high world number three ranking with, and a win in the final would move her to number two, only behind Ashleigh Barty.
She will meet Maria Sakkari in the final on Sunday, who broke down in tears after her hectic 6-2 4-6 6-1 win over Paula Badosa in the late match.
Despite Badosa having a higher first-serve rate than her opponent in the first set at 53.9 per cent, Sakkari was all over the second serve, winning nine out of a total 12 points.
After powering through the first set with flat hitting, the Greek world number six lost momentum in the second and forced play with rushed shot selection after getting broken early.
She still managed one of the shots of the match in trying to save that break of serve, scrambling across court to hit an underarm pass down the line.
Badosa kept her composure on serve to take the second set, winning 21 out of 29 points at an improved 72.9 per cent. Sakkari regrouped and exhibited her unique court coverage, however, taking the win after getting an early break.
Sakkari immediately broke down in tears afterwards, upon making her first WTA 1000 final and defeating the defending champion at Indian Wells.
The world number one started brilliantly by breaking the unseeded Romanian's serve on her first opportunity, and despite Cirstea responding, Swiatek rattled off the final four games of the opening set.
The 21-year-old Polish phenom would not stop there as she continued on a streak of eight consecutive games to jump ahead 4-0 in the second set, finishing the job in 83 minutes.
It is Swiatek's third consecutive tournament where she has made it to at least the semi-finals, having won the Qatar Open and reached the final of the Dubai Tennis Championships in February.
The last time she did not reach the semi-final in a tournament was in January's Australian Open, when she was sent packing in the fourth round by Elena Rybakina.
She will get a chance to avenge that defeat in the semi-final after Rybakina set up the rematch by getting the better of Karolina Muchova 7-6 (7-4) 2-6 6-4.
Rybakina, who became the first Kazakhstan-born player to reach the semi-final of a WTA1000 event since 2009, had a much more competitive affair.
In the razor-thin battle, both Rybakina and Muchova won exactly 106 out of 212 points, but the reigning Wimbledon champion and Australian Open finalist produced 14 break point opportunities to the Czech's six.
It will be the fourth overall meeting between Swiatek and Rybakina, and after the Pole took their first clash, Rybakina responded with back-to-back straight-sets victories.
The winner will earn a spot in the final, where they will meet the victor of Maria Sakkari and Aryna Sabalenka.
A savage 6-2 6-2 thrashing at the hands of Wimbledon champion Elena Rybakina came while Swiatek was suffering physically.
She was emphatically outplayed, and how much of a factor the injury was is unclear, with tests in the coming days set to dictate what happens next for the 21-year-old Pole.
Swiatek was asked about what Rybakina did well and said: "I feel like it's still more me and my mistakes. I'm also not feeling 100 per cent physically. I have a little discomfort in my rib, and we're going to consult with the medical team."
She said she would use the days leading up to next week's event in Miami as a chance to recover.
"In terms of the rib, we'll see, because I still have to run some tests and see what's going on. I don't know yet," she said after Friday's defeat.
"Honestly, I haven't played with a lot of injuries. It's a new situation for me. The last time I played with an injury, the only tournament I can remember, is Roland Garros in 2019, so I was pretty young.
"Now it's a totally different level. I have been playing, so there has been some fatigue all the time. I would say it's kind of constant, but I'm pretty sure that tomorrow or the day after will help in recovery."
Asked whether it was a problem that could prevent her playing in Miami, Swiatek said: "No, for now I'm preparing to play, but we'll see what the next days are going to tell us. I don't know yet."
Swiatek last year won both Indian Wells and Miami to complete the 'Sunshine Double' in the early stages of a 37-match winning run that ended with a third-round Wimbledon defeat to Alize Cornet.
While Swiatek seeks medical expertise, Rybakina goes on to face Aryna Sabalenka in Sunday's Indian Wells trophy match, a repeat of the Australian Open final that Sabalenka won to earn a first grand slam singles title.
It is the third time this century that the WTA Indian Wells showpiece match has featured the same line-up as the Melbourne Park final after 2000 (Lindsay Davenport and Martina Hingis) and 2012 (Maria Sharapova and Victoria Azarenka).
The 21-year-old Pole, who won last year's Indian Wells, had match point at 6-0 5-0, before Liu rallied back on serve to avoid the ignominy of a double-bagel defeat, with Swiatek eventually winning 6-0 6-1.
Swiatek was in a dominant mood, winning 57 of 83 points for the match and converting five of nine break points generated. She dropped only 11 points in seven service games.
The three-time grand slam champion is 13-3 on the season, with all 13 wins coming in straight sets. In five of those matches, she has dropped just one game.
Former US Open winner Emma Raducanu moved into the third round with a 7-6 (7-3) 6-2 win over 20th seed and 2023 Australian Open semi-finalist Magda Linette.
Raducanu's win meant she has put together back-to-back victories for the first time since September, setting up a clash with 13th-seed Beatriz Haddad Maia after she beat Katerina Siniakova 5-7 7-6 (7-4) 6-3.
Fourth seed Ons Jabeur fought back from a set down to prevail over Magdalena Frech 4-6 6-4 6-1 in one hour and 44 minutes.
Former US Open champion Bianca Andreescu also overcame an early deficit to win 4-6 6-4 6-3 over Peyton Stearns.
Reigning Wimbledon champion Elena Rybakina got the edge in a tight two-set clash with 2020 Australian Open winner Sofia Kenin, triumphing 7-6 (8-6) 7-6 (7-5) in two hours and 10 minutes. Rybakina fought back from 4-1 down in the second frame.
Fifth seed Caroline Garcia overcame a wobble to win 6-1 6-7 (4-7) 6-4 over Hungary's Dalma Galfi, with 30th seed Leylah Fernandez her next opponent after beating Emma Navarro 6-2 6-4.
Two-time major winner and three-time US Open finalist Victoria Azarenka was the big casualty from the day's play, losing 7-6 (7-1) 6-3 to 2021 Australian Open semi-finalist Karolina Muchova.
Swiatek started shakily as her serve was broken in the first game of the match, and although she got it back instantly, both competitors ended up creating eight break point opportunities each in a closer-than-expected match.
She will meet England's Emma Raducanu in the fourth round after the resurgent 20-year-old collected her best win of the year, defeating 13th seed Beatriz Haddad Maia 6-1 2-6 6-4.
Raducanu, the 2021 US Open champion, has begun to work her way back up the rankings. Having come into the tournament ranked 77th in the world after an injury-riddled season, she has now won four of her past five matches, with her only loss in that span coming against world number six Coco Gauff at the Australian Open.
World number five Caroline Garcia was pushed to a third set for the second match in a row, but prevailed 6-4 6-7 (7-5) 6-1 against Leylah Fernandez, booking a clash against Romania's Sorana Cirstea after she won 6-3 6-1 against fellow unseeded competitor Bernarda Pera.
Karolina Muchova kick-started a great day for the Czech Republic representatives as she got the better of Italy's Martina Trevisan 6-4 3-6 6-4, and Marketa Vondrousova kept it going with a 7-6 (7-5) 6-4 victory over world number four Ons Jabeur.
Reigning Wimbledon champion Elena Rybakina is shaping up as a threat to win it all, yet to drop a set this week following her 6-3 7-5 triumph over Paula Badosa.
Ukrainian Tsurenko had been due to face Belarusian Aryna Sabalenka in the third round on Sunday, only to pull out for what had initially been put down to "personal reasons".
She later revealed her decision was down to a panic attack triggered by a chat with WTA chief executive Steve Simon about tennis's response to Russia's invasion of Ukraine.
Swiatek offered her full support to Tsurenko and wants more focus to be on Ukrainian players during a hugely challenging period, rather than on Russian and Belarusian players.
"I totally understand why she withdrew. I respect Ukrainian girls so much," said the world number one, speaking after her 6-3 6-1 win over Emma Raducanu in the last 16 on Tuesday.
"If a bomb landed in my country or if my home was destroyed, I don't know if I could handle that and compete.
"You have to really mentally be there to compete every week. So I get that she wasn't ready to do that.
"I feel more should be done to help Ukrainian players. Everything we discuss in tennis is about Belarusians and Russians, if they should be allowed, what's going on with them.
"I don't think that's right. We should focus more on helping Ukrainian players and providing them with everything they need.
"They basically have to take care of all their families, and there's a lot of baggage on their shoulders."
Swiatek, who wears a Ukrainian flag on her cap, called out Anastasia Potapova earlier this week after she wore a Russian football shirt on court at Indian wells.
Potapova, allowed to compete in events as a neutral athlete, sported a Spartak Moscow jersey ahead of her 6-3 4-6 5-7 defeat to Jessica Pegula on Monday.
"To be honest, I was surprised," Swiatek said. "I thought the player realised that she should not, even if she is a fan of the team, show her views in this way at such times."
Top seed Swiatek believes the situation could have been avoided had the WTA set out clear guidelines regarding the highly charged political situation.
"It's a tough situation. It's pretty emotional as I feel like these situations with people wearing Russian football shirts because we didn't have proper leadership," Swiatek said.
"There is a lot of tension in the locker room that is obviously going to be there, because there is a war.
"But maybe there would have been a little bit less [tension] if WTA put some action in place at the beginning to kind of explain to everybody what is right and what is not."
Swiatek resumes her Indian Wells title defence against Sorana Cirstea in the quarter-finals on Thursday.
American Brad Gilbert, a former tour player who has worked with stars including Andre Agassi and Andy Murray, was taken aback by the tantrum from Kyrgios after a three-set defeat to Rafael Nadal in Indian Wells.
Kyrgios went to the net to shake hands with Nadal, who won 7-6 (7-0) 5-7 6-4 to reach the semi-finals.
But moments later he thrashed his racket against the ground. It bounced up high, travelling half the length of the court and causing a ball boy to take evasive action, stepping out of the way to avoid being hit and potentially hurt.
Kyrgios scornfully answered reporters' questions about the incident after the match, describing it as "a complete accident".
However, the 26-year-old unmistakably lost control in front of a full stadium and could face punishment as a result.
Gilbert wrote on Twitter: "Ridiculous to do that after such a good match, the penalty should be severe."
Gilbert questioned whether that would happen, given the ATP, which runs the men's tour, only handed a suspended eight-week ban to Alexander Zverev, plus a fine, after the world number three violently hit his racket against an umpire's chair.
"Unfortunately ATP lost the plot with Zverev situation and not a good look for kids and our sport," Gilbert wrote.
The 60-year-old Gilbert, who also coached Andy Roddick, said there was "absolutely no reason to snap on court after the match".
He added: "The stick could have easily gone anywhere like the stands and hit someone, seriously awful to see that in front of great crowd."
Kyrgios posted an exchange of text messages with the ball boy, and said he would give him a racket as a token of apology.
Saying sorry for the incident, Kyrgios wrote: "Didn't want it going anywhere near you to be honest."
Ruud, the third seed, joined second seed Stefanos Tsitsipas with an early exit after a timid display, with just 17 winners to go with 17 unforced errors against Chile's Garin.
Meanwhile, Garin took his opportunity against the world number four with both hands, rattling off 39 winners with 24 unforced errors as he made the decision to take the match on and not die wondering.
Garin, who already defeated 29th seed Yoshihito Nishioka in the second round, will meet his third seeded opponent in a row in the quarter-final when he takes on Spain's 23rd seed Alejandro Davidovich Fokina.
Davidovich Fokina eliminated 13th seed Karen Khachanov 6-3 1-6 6-4, but it was still a strong day for the Russians as top hopefuls Daniil Medvedev and Andrey Rublev advanced.
Medvedev, the fifth seed, was tested in his 6-2 3-6 6-1 victory over Belarus' Ilya Ivashka, while sixth seed Rublev saw off France's Ugo Humbert 7-5 6-3 without much issue.
Waiting for Rublev in the quarter-final is Briton Cameron Norrie after his 6-7 (5-7) 7-5 6-2 battle against Taro Daniel, while Alexander Zverev beat Emil Ruusuvuori 7-5 1-6 7-5 to book a tantalising clash with Medvedev.
In a poor day for the Australians, Jason Kubler went down 6-3 6-2 against 14th seed Frances Tiafoe, and Jordan Thompson could not follow up his incredible upset against Tsitsipas, falling 6-3 7-6 (8-6) to Chile's Alejandro Tabilo.
Alcaraz was in control, winning the first set in 36 minutes before racing to a 2-0 lead inside 10 minutes before the Briton withdrew. Draper had battled the injury in the latter stages of Monday's win over Andy Murray.
Despite that, the Spaniard looked in good touch, setting up a quarter-final meeting with eighth seed Felix Auger-Aliassime, who has a 3-0 head-to-head record against him.
"I felt the ball really well. I'm really happy with that part," Alcaraz said. "I would say I returned well, I hit great shots. I finished the match with confidence in my shots, to come into the next round with more confidence."
Auger-Aliassime saved six match points in a dramatic triumph over 17th seed Tommy Paul to reach the last eight, winning 3-6 6-3 7-6 (8-6) in two hours and 48 minutes.
The Canadian trailed 0-40 on serve at 5-6 in the deciding set before winning the next five points. He repeated that feat, down 3-6 in the tie-break, capitalising on his first match point. Auger-Aliassime hit 31 winners for the match, along with 51 unforced errors.
Fifth seed Daniil Medvedev fought back from a set down and a rolled ankle to progress past Alexander Zverev 6-7 (5-7) 7-6 (7-5) 7-5 in three hours and 10 minutes.
Medvedev rolled his ankle in the sixth game of the second set, going down in pain but played on, in his longest-ever three-set match. The victory is the Russian's 17th in a row. Zverev committed 50 unforced errors across the match.
The Russian will take on Alejandro Davidovich Fokina in the last eight, with the Spaniard winning 6-3 6-4 over Chilean qualifier Cristian Garin.
Jannik Sinner cruised past Stanislas Wawrinka 6-1 6-4 in one hour and 39 minutes to move into the last eight where he will face reigning champion Taylor Fritz. The American won 6-4 6-3 over Hungary's Martin Fucsovics in one hour and 41 minutes.
British 10th seed Cameron Norrie will play 14th seed Frances Tiafoe in the other quarter-final, with the former winning 6-2 6-4 over the higher-ranked Andrey Rublev. Tiafoe won 6-4 6-4 over Alejandro Tabilo in 83 minutes for his 150th career win.
The fifth seed was taken all the way to a third-set tie-break by Sock, which he trailed 5-3 before recovering to claim a 7-6 (7-5) 3-6 7-6 (7-5) victory in a gripping contest.
Sock, ranked 140 places below his opponent, put his strong forehand to good use to hold in a first set that went the distance but was undone by some unforced errors.
After responding brilliantly by taking the second set, after once again holding his serve, the American looked to be heading for defeat when 40-0 down at 5-6 in the third set.
However, he dug deep to force another tie-break and was within two points of a big victory, only for two more unforced errors to cost him a place in the last 32.
"It was a crazy battle; we both left everything out there," Tsitsipas said. "Jack played incredibly well at times but I was able to bring out the best in my game at the end.
"I proved I could play aggressive tennis and stay calm at the same time."
Tsitsipas will now face another home hopeful in Jenson Brooksby, who saw off Karen Khachanov 6-0 6-3 earlier in the day.
Jannik Sinner battled to a 6-3 6-3 win over Laslo Djere elsewhere in Saturday's action, while Denis Shapovalov and defending champion Cameron Norrie also advanced.
Fabio Fognini withdrew from his meeting with Nikoloz Basilashvili, who now awaits Norrie in the next round.
Korda had trained with Nadal earlier this week before the draw paired the two together – an eagerly awaited encounter for the younger man.
Korda is such a big Nadal fan his cat is named after the Spaniard, but he caused some concern for the 21-time major champion and his other supporters on Saturday.
Having talked up the meeting, it looked as though the occasion might get the better of Korda as he quickly fell 4-0 down in the opener.
Nadal had not dropped a set since victory at the Australian Open – one of three tournaments he has entered this year and three tournaments he has won.
But that perfect 15-0 record suddenly came under threat in the second set, as Korda sought to prolong his dream match-up and stunned his hero 6-1.
Suddenly, Nadal was forced to face down one of his biggest fans in a decider and initially struggled badly, falling two breaks down, with Korda serving for the match at 5-2.
This time the nerves did get to Korda, who lost four games in a row before stopping the rot to reach a tie-break.
There, Korda did briefly hold a mini-break lead, but that was only as part of a sequence of five consecutive mini-breaks that took the match away from him, Nadal prevailing 6-2 1-6 7-6 (7-3).
"I feel very, very lucky today to be through, honestly," Nadal said afterwards.
Korda could at least enjoy his consolation prize: compliments from Nadal, who had won their only prior meeting en route to his 2020 French Open title.
"Sebastian was playing some fantastic tennis and I'm sorry for him," Nadal said. "He had chances, but that's tennis.
"He's very young, he has an amazing future. I wish him all the best."
Up next for Nadal is Dan Evans, whose compatriot Cameron Norrie – the defending Indian Wells champion – also advanced with a straight-sets win over Pedro Martinez.
Kontaveit was the second-highest seed remaining in the tournament entering Monday's play, and appeared to be on her way through to the fourth round after breaking twice in the opening set.
Yet Vondrousova got the better of her Polish opponent in a topsy turvy second set, forcing a decider that starter in frantic fashion, with a concession of serve in each of the opening five games.
Vondrousova held to end that street yet was pulled back to 4-4 by a resurgent Kontaveit, though the Czech world number 33 eventually closed the match out at the fourth time of asking in the tie-break to tee up a clash with Veronika Kudermetova.
The 21-time grand slam winner is set to sit out the Indian Wells Open and Miami Open after the US extended the requirement for all non-American nationals to be vaccinated.
Djokovic's participation at August's US Open may also be in doubt should those requirements, which are currently in place until April 10, continue to be extended.
But having also been forced to miss events in the likes of the US, Canada and Australia last year, Djokovic accepts he may have to do the same in 2023.
"I don't think there's anything official yet, so when it is we can speak about it," Djokovic told reporters on Thursday when asked about the US restrictions.
When told the rules have been certified by the US Transportation Security Administration, Djokovic replied: "I mean, if it is official then it is – what can I do? Nothing.
"You know my position, so it is what it is. I'm hoping [to play], but if I can't go, I can't go."
Djokovic, cleared to compete in Australia this year, was speaking after defeating Quentin Halys 7-6 (7-3) 7-6 (7-5) in the last 16 of the Adelaide International.
The 35-year-old, who beat Constant Lestienne in straight sets in his opening singles match of 2023, trailed 5-2 in the first set but recovered well and then edged the second set.
"It was a great performance from my opponent today and I want to congratulate him for a great fight," Djokovic said in his on-court interview. "He played like a top-10 opponent.
"He was serving big, hitting his spots and on a fast court like this it's tough to break, so two tie-breaks is a realistic score in today's match. I'm glad to overcome the challenge."
Djokovic will now face Denis Shapovalov, who saw off Roman Safiullin 6-4 6-3, for a place in the semi-finals.
"Denis is one of the most complete players out there," Djokovic said of his next opponent. "He has a very dynamic style of tennis.
"I haven't played him for a while so I'm looking forward to it. Every match from here gets tougher."
Sebastian Korda also advanced on Thursday with a 6-4 6-4 victory against Roberto Bautista-Agut, while Jannik Sinner beat Thanasi Kokkinakis 7-6 (7-2) 6-4.
At the Maharashtra Open in Pune, top seed Marin Cilic withdrew from his quarter-final with Tallon Griekspoor due to a knee injury.
World number 95 Griekspoor will now face Aslan Karatsev for a place in the final.
Raducanu saw her 2022 season cut short by a problem with her right wrist, while a bout of tonsillitis caused her to miss last week's Austin Open.
The 2021 US Open winner was seen practising with strapping on both wrists on Wednesday, ahead of Thursday's Indian Wells opener against Danka Kovinic.
Asked about her fitness, Raducanu told BBC Sport: "The same issue that I had last year has started to flare back up.
"I've definitely been managing my load. It's something that has just come back, so I'm trying to be as cautious as possible. I'm going to do everything I can to be there tomorrow."
Raducanu's recent struggles with tonsillitis represented the latest setback of a year in which she has played just four competitive matches, and the 20-year-old has been frustrated by her lack of time on court.
"It affected me badly for the short term, so I haven't prepared much. I've probably never felt so sick in my life," Raducanu reflected.
"When it rains, it pours. This [the wrist injury] and the infection… it's obviously a challenge. My preparation hasn't been ideal. I played on the weekend and then I rested it. It's how you manage things when you aren't prepared."
