Alcaraz took just under an hour and 40 minutes to overcome his fellow Spaniard and friend 6-3 6-4, getting 67 per cent of his first serves in and winning 77 per cent of those.
Carreno-Busta struggled to keep the US Open champion at bay, facing 12 break points in all, and although he saved nine of them, his defiance was ultimately in vain.
"It is difficult to play against a friend like Pablo," Alcaraz said on-court after his win on Friday. "Every day we go and have dinner, lunch, together. Every week and we train together, so it is difficult to play against him.
"I also support him and want him to win every match. On court, there are no friends. You have to be focused and go for the match and that is what I did."
Alcaraz will face third seed Felix Auger-Aliassime in the final four after the Canadian defeated Alexander Bublik 6-2 6-3.
The other semi-final will see Roberto Bautista Agut play Holger Rune after the Spaniard beat Stan Wawrinka 7-5 7-6 (7-5) and the Danish teenager defeated Arthur Rinderknech 7-6 (7-0) 6-2.
In Austria, top seed at the Vienna Open Daniil Medvedev beat Jannik Sinner 6-4 6-2 to advance to the last four, where he will play Grigor Dimitrov after the Bulgarian overcame Marcos Giron 6-3 4-6 6-4.
The winner of that contest will face either Denis Shapovalov, who beat Dan Evans 6-3 6-3, or Borna Coric after the Croatian came through against Hubert Hurkacz 6-4 6-7 (2-7) 7-6 (7-5).
Spanish second seed Bautista Agut had dashed past Andy Murray and Alejandro Davidovich Fokina for the loss of just three games in Doha, but Khachanov proved far more obdurate.
After a slow start, eventually Bautista Agut picked up the pace and emerged a 2-6 6-3 7-5 winner in two hours and 24 minutes of toil, earning a shot at Georgia's Nikoloz Basilashvili in Saturday's final.
Bautista Agut praised Russian Khachanov for making him scrap for the win.
"He was playing very fast," said Bautista Agut, quoted on the ATP website. "He was playing very solidly, he was defending very well and he hit many unbelievable passing shots. I had to play incredibly well tonight. I enjoyed tonight so much."
Third seed Basilashvili is the defending champion this week and made light work of France's Arthur Rinderknech, tying up a 6-4 6-2 victory.
In Marseille, Greek top seed Stefanos Tsitsipas was stunned by Russian qualifier Roman Safiullin in the Open 13 quarter-finals. World number 163 Safiullin had a staggering 13 break points against the under-performing Tsitsipas serve, and although 11 of those were saved, the two that were not decided the match.
Safiullin, for his part, faced one break point and saved it on the way to a 6-4 6-4 victory. He made his presence felt at the ATP Cup in Australia at the start of the year and, although results have been disappointing since, the 24-year-old is doing well again in France this week.
Next for Safiullin will be last week's Rotterdam champion Felix Auger-Aliassime, who saw off Belarusian Ilya Ivashka 6-3 6-4 in the last match of the day. After losing his first eight finals on the ATP Tour, Auger-Aliassime may well be closing in on a second title in eight days.
Saturday's other semi-final will see Russian second seed Andrey Rublev tackle Frenchman Benjamin Bonzi, who reached the last four of a main-tour event for the first time by crushing Aslan Karatsev 6-1 6-3.
Rublev dug deep to edge out French wildcard and former top-10 player Lucas Pouille 6-3 1-6 6-2.
Rinderknech, who sits 65th in the world rankings, had not recorded a Tour-level victory before 2021 but has now triumphed 15 times after cruising past Delbonis 6-4 6-4.
The Frenchman will meet eighth seed Dusan Lajovic in the second round in Antwerp, after the Serbian downed Richard Gasquet 7-6 (7-3) 6-1 on Monday.
The other first-round clash in Belgium saw Alexei Popyrin capitulate in the third set as he succumbed to a 4-6 6-3 0-6 defeat against world number 62 Botic van de Zandschulp.
Americans Jenson Brooksby and Brandon Nakashima also booked their places in the main draw. Brooksby defeated Norbert Gombos 6-4 6-2, while Nakashima overcame Pierre-Hugues Herbert 6-2 6-4.
Meanwhile in Russia, Cilic – who has claimed the crown in Moscow twice previously – recovered from a first-set scare in his round-of-32 tie with qualifier Damir Dzumhur, eventually triumphing 6-7 (4-7) 6-1 6-1.
John Millman experienced similar difficulties, with Benjamin Bonzi claiming the first set before the Australian succeeded 6-7 (5-7) 6-4 6-3 to set up a potential second-round match against fifth seed Alexander Bublik.
Huesler arrived in Montpellier on a high from victories over German duo Alexander Zverev and Oscar Otte for Switzerland in Davis Cup qualifiers last weekend.
The left-hander saw off 18-year-old Frenchman Van Assche 6-3 3-6 6-3 and will get a chance to improve his perfect record against Rune to 3-0.
Italian Lorenzo Sonego sent eighth seed Benjamin Bonzi packing with a 6-4 6-3 win, while French-born American Maxime Cressy progressed with a 6-3 6-2 defeat of Antoine Bellier.
Arthur Rinderknech and Quentin Halys also advanced on home soil, along with Marton Fucsovics and Filip Krajinovic.
Kokkinakis was beaten by Gael Monfils in the semi-final of the Adelaide International 1 last weekend, but the 25-year-old got his hands on the trophy on Saturday after a 6-7 (6-8) 7-6 (7-5) 6-3 win.
The Australian saved two match points in a semi-final defeat of Marin Cilic and showed his fight again to deny Rinderknech a first title.
Kokkinakis has had a tough time with injuries since rising to a career-high ranking 69 as a teenager in 2015, but he has shown what he is capable of early in the season ahead of the Australian Open.
There were no break point in the first two sets, but Frenchman Rinderknech failed to hold twice in the decider on a special day for Kokkinakis.
Kokkinakis said: "I wouldn't want to win my first title anywhere else. To my family, friends and coaches, what a ride it's been. You have seen me at my lowest lows and now the highest high. It's been a serious journey. For now, I am so happy.
"I've been playing and practising on this court since I was eight or nine years old, coming here before school every day. I love this court so much."
Kokkinakis will play qualifier Yannick Hanfmann in the first round of his home grand slam next week, while Rinderknech takes on Alexei Popyrin at Melbourne Park.
World number four Medvedev fell to a 6-4 6-7 (7-9) 6-3 loss against three-time major winner Wawrinka, who will next meet Mikael Ymer after his straight-sets win over home favourite Gregoire Barrere.
Second seed Hurkacz did not experience such struggles against Thiem as the Pole cruised to a 6-3 6-4 as he served 12 aces in a dominant performance in Metz.
Hurkacz will face Arthur Rinderknech in the next round after the Frenchman battled to a 7-6 (13-11) 6-3 triumph over fifth seed Nikoloz Basilashvili.
Alexander Bublik, the seventh favourite in France, was also made to work for his progress to the quarter-finals, downing Emil Ruusuvuori 6-7 (4-7) 6-4 6-3.
Fourth seed Holger Rune awaits Bublik after Benjamin Bonzi retired due to injury when 6-4 4-1 down against the Dane.
Lorenzo Sonego coasted through his second-round clash to defeat Gilles Simon 7-6 (7-2) 6-4 to tee up a last-eight clash with Sebastian Korda.
Murray earned his fourth Tour-level quarter-final spot of 2022 by beating Pedro Cachin, but American Korda defeated the former world number one 6-4 1-6 6-1.
Korda will face Arthur Rinderknech in the last four after he upset second seed Pablo Carreno Busta, taking an epic final-set tie-break to triumph 4-6 6-3 7-6 (18-16).
The other side of the draw will play host to an enticing semi-final meeting between Dominic Thiem and top seed Andrey Rublev after they secured straight-sets wins over Francisco Cerundolo and Tommy Paul respectively.
Thiem said after his 6-4 6-3 triumph over Cerundolo: "From the first match on, I have felt great on this court.
"It is very important for me as I am trying to climb up the rankings. The semi-finals at an ATP event is helping a lot."
Meanwhile, top seed Felix Auger-Aliassime beat Brandon Nakashima 6-3 6-4 to reach the Firenze Open semi-finals, where he will face home favourite Lorenzo Musetti.
The third seed from Italy downed Mackenzie McDonald 6-3 6-2, but fellow seed Alexander Bublik went down 3-6 7-5 6-1 to J. J. Wolf.
The world number nine battled through an up-and-down opener before remaining patient to seal the second set and the match on Thiem's serve, taking a 6-4 6-4 victory.
Russian Rublev has now won eight successive sets of tennis against the 2020 US Open champion, and he is one win away from his fourth title of 2022 after triumphs in Belgrade, Dubai and Marseille.
Speaking on court after the win, Rublev said: "I was lucky I played a really good game and Dominic helped me out a little bit.
"Then I felt more confident and I was able to win in two sets, which was the most important thing. This week I have been playing really well, and I'll try to show my best tennis of the week tomorrow."
Korda will be Rublev's opponent on Sunday after the American saw off France's Arthur Rinderknech for a 7-6 (7-2) 6-3 win.
Meanwhile, at the Firenze Open, top seed Felix Auger-Aliassime saw off home favourite Lorenzo Musetti 6-2 6-3, moving one step closer to a second ATP Tour title.
The Canadian will face JJ Wolf in the final in Florence, after the American clinched a 6-4 6-4 win over Sweden's Mikael Ymer.
ATP world number four Tsitsipas is one of the headline names in action at the event, which is acting as a warm-up tournament for the Australian Open.
After going a set down to his Bulgarian opponent in his first game of the inaugural tournament, Tsitsipas hit back with a strong second set before holding his nerve in a tense tie-break in the decider, securing a 4-6 6-2 7-6 (7-4) win.
Tsitsipas's team-mate Despina Papamichail continued Greece's strong start, also coming from a set down to beat Isabella Shinikova 3-6 6-4 6-1.
Great Britain opened with a pair of victories, Cameron Norrie and Katie Swan earning straight sets triumphs over their Australian counterparts in Sydney.
Norrie, who was initially set to play Nick Kyrgios prior to the Wimbledon finalist's withdrawal due to an ankle injury, eased to a 6-3 6-3 victory over Alex De Minaur, while Swan defeated Zoe Hives.
The United States are also taking a 100 per cent record into day two of the tournament, after Taylor Fritz and Madison Keys overcame Jiri Lehecka and Marie Bouzkova respectively, while France pair Arthur Rinderknech and Alize Cornet got off to winning starts against Argentina's Francisco Cerundolo and Maria Lourdes Carle.
In Brisbane, Swiss hope Belinda Bencic secured a 7-6 (7-0) triumph over Yulia Putintseva of Kazakhstan and Beatriz Haddad Maia, the Brazilian world number 15, dispatched Italy's Martina Trevisan 6-2 6-0.
Ahead of a tilt at the French Open, for which he is among the favourites, world number five Tsitsipas has been tuning up his game at this week's ATP 250 tournament.
The Greek star was sharp in posting a 6-3 6-4 win over Japan's Yoshihito Nishioka, and 19-year-old Italian Musetti awaits him on Saturday.
Tsitsipas dropped just four games when he crushed Musetti in an Acapulco semi-final in March, but he senses more of a threat this time from the exciting youngster.
"We played in different conditions. Acapulco was a hardcourt match and with altitude," said Tsitsipas, speaking on Amazon Prime. "The conditions here are different. He's someone who enjoys playing on clay.
"We share a similar game style I think with a one-handed backhand, which is beautiful to see, but tomorrow it's going to be serious business I knew he can play good on this surface. I know he can elevate his game, so it's important for me to be in the semi-finals."
Musetti overcame Slovenian Aljaz Bedene 6-3 7-6 (7-2) in their quarter-final, scrambling through a chaotic second set in which he trailed 5-2 at one stage but then reeled off four straight games, only to fail to serve out.
Thankfully for the youngster, he pulled through the tie-break.
"It was a crazy end," said Musetti. "I was 6-5 up, and at 30-30 played a really bad volley and hit an underarm serve. Sometimes I go out of my mind. I am really proud of myself as I was 2-5 down in the second set and I stayed focused. I tried to play each point at my best."
Russian Karen Khachanov marked his 25th birthday with a 6-1 7-6 (7-3) win over Frenchman Richard Gasquet, veteran doyen of the single-handed backhand.
Khachanov faced a wait to learn who he must face in the semi-finals, however, with Cameron Norrie and Arthur Rinderknech level at one set all overnight, after rain forced an early end to play.
At the Geneva Open, Norway's Casper Ruud will tackle Canadian Denis Shapovalov in Saturday's final.
Ruud saw off Spaniard Pablo Andujar 6-3 6-2, while Shapovalov earned a 6-4 7-5 win against Uruguayan qualifier Pablo Cuevas.
On the same day fellow countryman Roger Federer would hang up his racquet at the Laver Cup, Wawrinka was forced to go all the way by his opponent in Metz, eventually winning 6-4 4-6 7-6 (7-5).
The three-time grand slam champion, whose injury struggles and form have seen him tumble to 284 in the world rankings, served up seven aces to Ymer's two, and made no double faults.
Victory moves him into the last four, where he will meet seventh seed Alexander Bublik after the Kazakh saw off Holger Rune in another three-set encounter with a 6-3 5-7 6-4 win.
Defending champion Hubert Hurkacz is also through to the semi-finals after making quick work of home favourite Arthur Rinderknech, winning 6-3 6-2.
The world number 10 will face Lorenzo Sonego next after the Italian also came through his quarter-final in straight sets against Sebastian Korda.
