Nadal remained on track in his bid to win a 20th grand slam title despite wasting chances against Federico Delbonis in Melbourne on Thursday.
The seeds have been relatively untroubled in the opening rounds in Australia, and they are on a collision course heading into the end of the first week and into the second.
Medvedev, Zverev and Wawrinka were also among the winners in the top half of the draw.
NADAL BATTLES INTO ALL-SPANISH THIRD-ROUND CLASH
Nadal converted just three of 20 break points to overcome Delbonis 6-3 7-6 (7-4) 6-1.
The Spanish star was wasteful before winning in two hours, 30 minutes, while he apologetically kissed a ball girl after striking her with a wayward forehand late in the victory.
Awaiting Nadal is Pablo Carreno Busta, the 27th seed having got past German qualifier Peter Gojowczyk 6-4 6-1 1-6 6-4.
Nadal has won his previous four meetings with Carreno Busta.
MEDVEDEV, ZVEREV AND WAWRINKA ADVANCE
Runner-up to Nadal at last year's US Open, fourth seed Medvedev was too strong for Spain's Pedro Martinez as he won 7-5 6-1 6-3.
Another member of the 'Next Gen', Zverev got the job done against Egor Gerasimov, winning 7-6 (7-5) 6-4 7-5.
Zverev will meet Fernando Verdasco after the Spanish veteran upset 26th seed Nikoloz Basilashvili in four sets.
Wawrinka, the 2014 champion, was pushed hard by Andreas Seppi, but the Swiss made it 10 wins in 14 meetings with the Italian veteran, securing a 4-6 7-5 6-3 3-6 6-4 victory.
John Isner awaits Wawrinka after the American served 32 aces in a 6-4 6-3 6-3 win against Chilean qualifier Alejandro Tabilo.
Dominic Thiem (fifth seed) and David Goffin (11th) were pushed to five sets before overcoming Alex Bolt and Pierre-Hugues Herbert respectively.
KYRGIOS, KHACHANOV SET UP CINCINNATI REMATCH
Nick Kyrgios and Karen Khachanov were both tested before setting up a third-round clash.
Kyrgios got past Gilles Simon 6-2 6-4 4-6 7-5, while Khachanov needed four hours, 34 minutes to edge Mikael Ymer 6-2 2-6 6-4 3-6 7-6 (10-8).
Khachanov won his previous meeting with Kyrgios in Cincinnati last year, but it was a clash best remembered for the Australian's outburst at umpire Fergus Murphy that resulted in a 16-week suspended ban and fine.
Gael Monfils, Andrey Rublev and Taylor Fritz were among the other seeds to win through on Thursday.
Only one adrift of Roger Federer's record haul of 20 grand slams, Nadal has reached four finals at Melbourne Park without success since claiming his sole Norman Brookes Challenge Cup 11 years ago.
Nadal did, however, sweep the French and US Open titles last year after he was completely outclassed by Novak Djokovic in the Australian Open decider.
We take a closer look at the 33-year-old as he prepares for another match in Melbourne.
Form and results
Nadal had little problems in his straight-sets win against Bolivia's Hugo Dellien. Forced to grind early, the top seed eventually outclassed the world number 73 in just over two hours on Rod Laver Arena. A total of 38 winners and eight breaks proved the difference for the relentlessly consistent Nadal.
R1: bt Dellien 6-2 6-3 6-0
Next up
Nadal - who boasts a 3-0 head-to-head record - will look to maintain his perfect run against Delbonis, though this is the first clash outside of South America. Argentine veteran Delbonis advanced to the second round thanks to a straight-sets victory over Joao Sousa on Tuesday. This is only the second time Delbonis has made it beyond the first round of the Australian Open - he reached the third round in 2016.
Draw
An all-Spanish affair could await Nadal in the third round, with Pablo Carreno Busta looming depending on results. Things could get juicy in the fourth round if the superstar makes it that far. Nick Kyrgios, who has history with Nadal, might stand in the way of a quarter-final berth.
What he said
"I have been a break up twice in the fifth set and I lost. Another time I have been injured in a final, of course, against a great opponent. At that time against an opponent that in that moment I have been, like, 14-0 against him on the head-to-head record. I had a problem on my luck in the final. Then other times, like 2018, I get injured against [Marin] Cilic. I went through a couple of things, more than in New York honestly. But I don't know. Maybe the conditions are better for me in New York than here."
Nadal wasted numerous break points on Rod Laver Arena, needing two hours, 30 minutes to overcome Delbonis 6-3 7-6 (7-4) 6-1.
The world number one was below his best, but was still good for Delbonis, who had won just 10 games in his previous three meetings with Nadal.
The Spanish star remained on track in his bid to join Roger Federer on a men's record 20 grand slam titles, though, with countryman Pablo Carreno Busta awaiting him in the third round.
Nadal squandered six break points in a marathon 22-point second game, but would take his next chance when Delbonis sent a tame backhand into the net.
That solitary break would be enough for Nadal to win the opening set, crushing a forehand winner to take it in 49 minutes.
Delbonis dug himself out of a 0-40 hole to hold in the first game of the second set and saved two more break points in the fifth game.
Another three chances came and went for Nadal in the seventh game before an ace from Delbonis – who looked to be working his way into the contest – denied the Spaniard again in the 11th game.
A wonderful lob helped Nadal set up a 3-1 lead in the tie-break, an advantage he would not relinquish on his way to a two-sets-to-love lead.
Delbonis' resistance was finally broken and so was his serve in the fourth game of the third set as Nadal – who kissed a ball girl after a wayward forehand – booked his spot in the third round.
STATISTICAL BREAKDOWN
Rafael Nadal [1] bt Federico Delbonis 6-3 7-6 (7-4) 6-1
WINNERS/UNFORCED ERRORS
Nadal – 33/29
Delbonis – 22/43
ACES/DOUBLE FAULTS
Nadal – 8/1
Delbonis – 2/8
BREAK POINTS WON
Nadal – 3/20
Delbonis – 0/0
FIRST SERVE PERCENTAGE
Nadal – 69
Delbonis – 63
PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE
Nadal – 85/61
Delbonis – 65/44
TOTAL POINTS
Nadal – 116
Delbonis – 83
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.
Delbonis, who is seeded fifth and lost to eventual winner Pablo Carenno Busta last week in Hamburg, cruised to a 6-3 6-3 victory against Leandro Riedi as the Swiss player struggled to make home advantage count.
Seventh seed and loser of the other semi-final in Germany last week, Djere continued his good form and wasted no time in thrashing Brazilian Thiago Seyboth Wild 6-4 6-3.
The other game on day two saw Dennis Novak dispatch of Kacper Zuk 6-4 6-4 and that straight-sets victory means the Austrian will next face the number three seeded player Casper Ruud, who won the Nordea Open last week to secure his third ATP title and second of 2021.
Alongside Ruud, the three other top four seeds - Denis Shapovalov, Roberto Bautista Agut and Cristian Garin - will now enter the draw, after benefiting from byes in the first round of the competition.
There was a surprise at the Croatia Open in Umag, though. Fifth seed Aljaz Bedene went down 6-1- 6-4 to Marco Cecchinato, who will now challenge fellow qualifier Damir Dzumhur to set up a potential quarter-final clash with Richard Gasquet if the Frenchman makes it through his round-of-16 tie.
The 31-year-old Argentine, who is currently ranked 41st in the world, went down 6-4 6-2 to the 111th-ranked Spaniard.
Former top 10 player Fernando Verdasco was also beaten on Tuesday, going down to Argentine Sebastian Baez 7-6 (8-6) 7-5.
The 38-year-old Spaniard dropped out of the top 100 last year for the first time since 2004 after a difficult season with a long-term leg injury and COVID-19 prior to the French Open.
Baez will play Chilean third seed Cristian Garin in the second round, while Taberner will meet qualifier Alejandro Tabilo after he beat wild card Francisco Cerundolo 6-4 6-1.
Lucky loser Colombian Daniel Galan also progressed into the last 32 after a 7-5 6-3 victory over Bolivian Hugo Dellien, while sixth seed Albert Ramos-Vinolas triumphed 6-4 6-3 over Andrej Martin.
Top seed Ruud defeated Federico Coria 6-3 6-4 in the last eight on Friday to set up a semi-final against another Argentinian in Federico Delbonis.
Delbonis defeated Fabio Fognini 6-4 6-4 to make his first semi since losing to Pablo Carreno Busta in Hamburg last July.
The 31-year-old has not played an ATP Tour final since winning in Marrakech in 2016.
There will be a home representative remaining in the other half of the draw, too, although his identity is still to be confirmed.
Diego Schwartzman and Francisco Cerundolo were tied in the third set when rain saw play suspended for the day.
The winner of that match will play Fognini's compatriot Lorenzo Sonego, a straight-sets victor against Fernando Verdasco.
At the Dallas Open, there is an all American cast for the semi-finals – but top seed Taylor Fritz is not among those in the last four.
He lost a third-set tie-break to countryman Marcos Giron, whose reward is a match against Jenson Brooksby. Brooksby beat Australia's Jordan Thompson 6-3 6-0.
John Isner breezed through in straight sets and will face Reilly Opelka.
Eighth seed Delbonis lost serve twice in the first set against Roberto Carballes Baena but recovered well to claim a 7-5 6-1 victory in Marbella.
He will take on Norbert Gombos, who recovered to beat Juan Ignacio Londero 6-7 (3-7) 6-1 6-3, for a place in the quarter-finals of the clay-court event.
Kwon was made to do things the hard way against junior tennis world number one Rune, who took the match all the way.
Despite trailing 3-1 in the third set, seventh seed Kwon held his nerve to force a tie-break and prevailed 6-3 3-6 7-6 (7-4).
Ricardas Berankis is also through thanks to a 6-4 6-7 (5-7) 7-5 victory over Lucas Pouille in just under three hours.
Meanwhile, seeded pair Tommy Paul and Guido Pella fell at the first hurdle in the Sardegna Open to Yannick Hanfmann and Egor Gerasimov respectively.
Eighth seed Paul recovered after squandering a 4-1 lead in a first-set tie-break but fell 7-6 (10-8) 5-7 6-3, while seventh seed Pella lost 6-4 6-0 in straight sets to Gerasimov.
Elsewhere in Cagliari, Aljaz Bedene rallied past teenager Giulio Zeppieri 1-6 7-5 7-6 (7-3) and Laslo Djere eliminated Italian wildcard Federico Gaio 6-4 6-2.
Reigning champion Djokovic, who is seeking a sixth triumph in Rome, struggled to get going against Tsitsipas and trails 6-4 2-1 ahead of the scheduled resumption of play on Saturday.
The top seed lost serve in the first game and continued to make some uncharacteristic errors that saw him trail 4-1 at one point.
While Djokovic did earn a first break in the sixth game, Tsitsipas stood firm to take the opening set and was in total control when again breaking his opponent early in the next set.
However, soon after the Greek had opened up a 2-1 advantage, the worsening conditions led to a pause in proceedings and organisers were eventually forced to bring the day's play to an end.
Djokovic, who converted just one of his six break point opportunities, will return to the court on Saturday and will need to improve if he is to join Rafael Nadal in the final four.
Nadal exacted some revenge on Alexander Zverev earlier on Friday to reach the semi-finals for a 12th time.
The Spaniard lost to Zverev at the same stage of the Madrid Open seven days ago but responded to questions over his form by easing through this latest encounter.
Nadal, who saved two match points before beating Denis Shapovalov on Thursday, raced 4-0 ahead in the first set against Zverev and had little trouble seeing the job through.
Aiming for a record-extending 10th title in the Italian capital, Nadal saved all eight break points he faced in the second set to advance 6-3 6-4 in two hours.
"I played more solid than Madrid. Conditions are different," he said in his post-match interview. "Here the conditions are a little more normal. I was able to control a little bit more."
"I'm happy. I played a very solid match with not many mistakes, playing the way that I have to. It's an important victory for me against a great player."
Nadal will face Reilly Opelka for a place in the final, the American beating qualifier Federico Delbonis 7-5 7-6 (7-2) to reach his first ATP Masters 1000 semi-final.
Opelka entered the tournament on a six-game losing streak, but he kept his good run going in Rome by earning the only break of the opening set in the 12th game.
Both players held throughout the second set and it was big-serving Opelka who prevailed 7-2 in the tie-break.
The day's other quarter-final between Lorenzo Sonego and Andrey Rublev also fell victim to the bad weather and will get under way on Saturday.
Top seed Garin is aiming to win an ATP Tour event on home soil for the first time in Santiago.
The 24-year-old was made to work by Peruvian qualifier Juan Pablo Varillas in the last eight on Friday, but he prevailed 6-4 6-4.
Garin was broken first in either set yet responded instantly on each occasion.
"I would love to be able to do something important in this tournament," the Chilean said. "It is special and I hope I can continue to win.
"I am playing better, in a semi-final and I am excited to do better, but I prefer to go step by step, game by game."
Daniel Elahi Galan is up next, while the highest remaining seed besides Garin is Argentina's Federico Delbonis, the number eight.
That is because Facundo Bagnis set up a meeting with his compatriot by defeating fourth seed Laslo Djere.
Bagnis, who had already claimed the scalp of fifth seed Frances Tiafoe, dropped the first set but recovered to advance 4-6 6-3 6-3 at the ATP 250 tournament.
The 20-year-old Nakashima rallied to defeat Italian veteran Fabio Fognini 6-7(5), 6-1, 7-5 in the first round at the San Diego Open, setting up a second-round matchup with top seed Andrey Rublev.
After qualifying for the main draw at Wimbledon earlier this summer, Nakashima reached finals at Los Cabos and Atlanta in successive weeks, falling to John Isner in the latter finale. He then knocked Isner out of the US Open in the first round in straight sets.
Monday, he won 80 per cent of the points on his first serve, dialling up eight aces to just one for Fognini, who also double faulted 11 times.
Another Southern California native, Taylor Fritz, also advanced Monday, beating qualifier Salvatore Caruso 6-4 7-6 (2) to earn a second-round meeting with fourth seed Denis Shapovalov.
It was a welcome reprieve for the world number 39, who had lost five of his previous six matches dating to a quarter-final win over Reilly Opelka in Atlanta.
Earlier, world number 24 Aslan Karatsev opened the day's action by defeating Federico Delbonis 6-1 7-5.
Big-serving American Isner overcame Filip Krajinovic 7-6 (10-8) 6-4 and will face either Cameron Norrie or Kwon Soon-woo in the round of 32.
Isner is joined in the next round by Evans, who eased past Federico Delbonis 6-3 6-4 to set up a last-32 meeting with either Roberto Bautista Agut or Jenson Brooksby.
Fellow Briton Jack Draper also enjoyed a straight-sets victory, edging out Lorenzo Sonego 6-4 6-3 to book a clash with number six seed Andrey Rublev, who received a bye.
Monday's action will see wildcard Andy Murray face Dominic Thiem and 10th seed Jannik Sinner take on Tommy Paul.
World number 15 Monfils would have been expected to breeze through against Carballes Baena, whose lone ATP title came back in February 2018.
But Monfils was trounced in the first set and, despite coming back from a break down to win the second, he could not avoid a shock loss as Carballes Baena reversed a 4-1 deficit in the decisive tie-break on Wednesday.
Carballes Baena's triumph sets up a last-eight clash with eighth seed Federico Delbonis, who beat Thiago Monteiro 7-6 (8-6) 3-6 6-4 at the ATP 250 event in Serbia.
Dusan Lajovic also moved through to the quarters after easing past Jeremy Chardy 6-3 6-4, with Andrej Martin the fifth seed's opponent after upsetting third seed Nikoloz Basilashvili 6-1 4-6 7-6 (7-4).
Elsewhere, top seed Lorenzo Sonego suffered a second-round exit at the Emilia-Romagna Open as Sebastian Korda claimed a surprise win.
Korda entered the tournament with just one clay-court win to his name in 2021 but followed up a first-round success over Andreas Seppi with a 6-1 7-5 defeat of Sonego.
Yoshihito Nishioka is his next opponent after the Japanese saw off Lorenzo Musetti 6-3 6-2.
Jaume Munar and Richard Gasquet also progressed, as did Jan-Lennard Struff, Norbert Gombos, Marco Cecchinato and Tommy Paul.
Nadal – playing his first competitive tournament since the Australian Open – produced some highlight moments as he saw off Miomir Kecmanovic 6-2 7-5 in Acapulco on Wednesday.
A two-time winner of the ATP 500 event, world number two Nadal was a class above against his Serbian opponent to stay on course for the title.
After his powerful display, the 19-time grand slam champion will face Kwon Soon-woo for a spot in the semi-finals after the South African beat eighth seed Dusan Lajovic 7-6 (7-2) 6-0.
Australian Open semi-finalist Zverev was bundled out of the tournament by American qualifier Tommy Paul 6-3 6-4.
Zverev dropped his opening service game and it was a sign of things to come for the German star as Paul capitalised to eventually claim the biggest win of his career.
Next up for 22-year-old Paul is fifth seed John Isner, who downed fellow American Marcos Giron 6-3 7-6 (7-4).
Grigor Dimitrov saved two match points as he prevailed 6-7 (8-10) 6-2 7-6 (7-2) against Adrian Mannarino in a thriller.
Mannarino erased Dimitrov's 4-1 lead in the final set to earn a pair of match points but the Bulgarian rallied to set up a showdown with third seed Stan Wawrinka, who eased past Pedro Martinez 6-4 6-4.
Elsewhere, fourth seed Felix Auger-Aliassime was surprised 6-4 6-4 by Kyle Edmund and Taylor Fritz topped Ugo Humbert 6-4 6-1.
At the Chile Open in Santiago, seeds Casper Ruud, Hugo Dellien and Federico Delbonis all moved through to the quarters but Pablo Cuevas fell to qualifier Renzo Olivo.
Nadal, 34, has won the competition more times than anyone else in its history and looked in good shape as he returned to the court for the first time since losing to Stefano Tsitsipas in the Australian Open quarter-finals on February 17.
He needed just 81 minutes to get past the Argentinian qualifier 6-1 6-2 as he improved his record in the tournament to 72-5, breaking Delbonis' serve five times and only dropping his own once.
He is not getting carried away, however, with Grigor Dimitrov likely to provide a sterner test in the next round after beating Jeremy Chardy 7-6 (7-3) 6-4.
"It was solid match, I think. Of course, a very positive result. He's a good player on clay. [It was a] positive start for me," Nadal said in his post-match interview.
"I think I just really played a solid match. Nothing unbelievable, but nothing wrong. Just a solid match, a positive start. I think I did what I had to do."
On Dimitrov, Nadal added: "We've had some great matches. In Melbourne, of course... we played another great match in Beijing, another one in Shanghai. He's a good friend, a good guy, and a great player. It's going to be a tough test in my second round.
"It's going to be his third. I need to be ready for it. I hope to be ready for it. I am just excited to play a tough match very early in the tournament."
A little earlier in the day, world number one Djokovic was in a similarly unforgiving mood as he overcame the potentially tricky obstacle of Jannik Sinner, the Serbian and two-time Monte Carlo champion winning 6-4 6-2.
Like Nadal, Djokovic was back in action for the first time since the Australian Open – which he won – and appeared fresh as he gave the promising young Italian something of a lesson in game management, reaching 10 matches unbeaten at the start of a season for the sixth time.
"It feels great [to be back and] also playing in Monaco, where I reside," Djokovic said. "I have used this club as a training base for almost 15 years, so it feels like playing at home."
Despite the rather commanding nature of his win, Djokovic was keen to pay tribute to the 19-year-old Sinner, adding: "It was a very good encounter. I thought it was a great first match [and] a big challenge for me. Jannik is in form. He played the final [in] Miami and has been playing well. I just hung in there today and managed to find the right shots and the right game at the right time.
"He has got a lot of talent and he has proven that he is the future of our sport. Actually, he is already the present of our sport. He played a final [in an] ATP Masters 1000 [tournament] already. He is making big strides in professional tennis."
Dan Evans awaits Djokovic after an impressive 6-4 6-1 win over Miami champion Hubert Hurkacz, while Alexander Zverez and Andrey Rublev – the fifth and sixth seeds – moved into the next round with respective straight-set victories over Lorenzo Sonego and Salvatore Caruso.
There were mixed fortunes for the other two top-10 seeds in action on Wednesday, as Pablo Carreno-Busta defeated Karen Khachanov 6-2 6-3, but Diego Schwartzman was sent packing by Casper Ruud, the Norwegian winning 6-3 6-3.
World number one Djokovic is returning to action this week, having taken time away from the tour since banking an 18th grand slam title by winning the Australian Open in February.
He received a first-round bye, but waiting for him in the last 32 is Sinner, who on Tuesday saw off 2017 Monte Carlo runner-up Albert Ramos-Vinolas 6-3 6-4, again illustrating the 19-year-old Italian's great potential.
World number 22 Sinner is the only teenager ranked inside the top 80 in the men's game and is coming off his first run to a Masters final, at the Miami Open.
The switch from hard courts to clay is one that Sinner is having to deal with, and seeing off a specialist on the surface in round one represents an impressive start, although facing two-time former champion Djokovic will be a step up.
"It's always good for me to see what I can do on clay," Sinner said, quoted on the ATP website. "Obviously, I am not in the best form on clay now for the first week.
"But I think today was a solid match from my side. It was not easy. He's not giving [away] one point, so you have to stay there the whole match. I think I played a good match from my side."
Greek fourth seed Stefanos Tsitsipas reached the last 16 with a 6-3 6-4 win over Russian Aslan Karatsev, but there was disappointment at the same stage for Italian eighth seed Matteo Berrettini, beaten 7-5 6-3 by Spain's Alejandro Davidovich Fokina. Those were the only second-round matches of the day.
Surprise Miami champion Hubert Hurkacz made a winning start, battling to a 6-3 3-6 6-3 first-round success against Italian qualifier Thomas Fabbiano to reach round two.
Roberto Bautista Agut, Grigor Dimitrov, Pablo Carreno Busta and Fabio Fognini each booked places in round two thanks to straight-sets wins.
Qualifier Federico Delbonis was a 7-5 6-1 victor over France's Adrian Mannarino, meaning the Argentinian faces the ultimate test in clay-court tennis next, a tussle with Rafael Nadal, the 11-time former champion in Monte Carlo.
Nadal has won all four of their previous matches, and their fifth encounter will immediately follow the Djokovic-Sinner match on Wednesday.
Medvedev's first stint at the top of the ATP rankings ended swiftly when he lost in the third round at the Indian Wells Masters and was displaced by Novak Djokovic.
But the Russian has the opportunity to leapfrog Djokovic once more by making the semi-finals in Miami.
Before thinking about the latter stages of the Masters 1000 tournament, however, Medvedev first must master Murray, who looked in good nick on his return to Miami.
Murray has twice won this tournament but has not played it since 2016, meaning Thursday's match against Federico Delbonis was his Hard Rock Stadium debut.
Delbonis had won the pair's only prior meeting yet was outclassed 7-6 (7-4) 6-1 after a steady first set.
Medvedev and Murray have also only met once before now, with the world number two coming out on top, but the wild card is looking forward to the challenge.
"It's a big challenge for me, a big test," Murray said. "I've got a big training block after this tournament and it'll be a really good test for where my game's at and the things I need to work on as well against him. I'm looking forward to that."
That is not the only mouthwatering second-round tie, with Nick Kyrgios through to face Andrey Rublev.
However, Stefanos Tsitsipas has a slightly more straightforward task on paper after qualifier J.J. Wolf advanced past Daniel Altmaier.
Rinderknech, who is ranked exactly 100th in the world, picked up the biggest win of his career in style as he dispatched of second seed Agut with a comfortable 6-2 6-4 victory
In another upset, world number 155 Hugo Gaston laid down an early marker with a first-set demolition of Delbonis, who lost out to eventual winner Pablo Carreno Busta in the Hamburg European Open semi-finals last week, before he triumphed in three sets, 6-0 6-7 (2-7) 7-6 (7-3).
Fourth seed Cristian Garin cruised past Marc Polmans 6-3 6-0 to wrap the match up in less than an hour and seal his fifth ATP quarter-final of 2021.
Another semi-finalist in Hamburg, Laslo Djere survived a second-set scare to eliminate Zizou Bergs with a 6-2 4-6 6-2 win, which sets up a last-eight tie with Rinderknech.
At the Croatia Open in Umag, fourth seed Richard Gasquet battled past qualifier Alessandro Giannessi to secure a 7-6 (7-4) 6-4 victory.
Top seed Albert Ramos-Vinolas also progressed, winning 7-5 6-4 to eliminate Duje Ajdukovic on his home turf.
