Juan Martin del Potro’s dream comeback to Flushing Meadows continued on Monday as he advanced to the US Open quarter-finals.

World No. 142 del Potro, who was given a wild card into the main draw, is the lowest-ranked US Open quarter-finalist since the 174th-ranked Jimmy Connors 25 years ago.

The Argentine advanced when Dominic Thiem was forced to retire from their fourth-round clash due to a right leg injury. Del Potro was leading 6-3, 3-2 with a break in the second set.

The 27-year-old del Potro is playing in New York for the first time since 2013. The Tandil native captured his only Grand Slam championship at the US Open in 2009 (d. Federer), but since then his career has been blighted by wrist injuries.

Del Potro played just four matches and underwent two operations on his left wrist in 2015, before making his return to the ATP World Tour in February of this year. In his first tournament back he reached the semi-finals in Delray Beach (l. to Querrey) and last month he clinched the silver medal at the Rio Olympics, playing Andy Murray in the final.

Del Potro is yet to drop a set at the US Open, dispatching Diego Schwartzman, Steve Johnson and David Ferrer. The right-hander is bidding to reach his first major semi-final since Wimbledon 2013 (l. to Djokovic) and goes on to challenge Stan Wawrinka or Illya Marchenko.

Del Potro is set to return to the Top 100 in the Top 65 in the Emirates ATP Rankings after the US Open for the first time since 27 October, 2014.

The 23-year-old Thiem was through to the US Open fourth round for the second time after edging Pablo Carreno Busta on his 23rd birthday on Saturday. The Austrian remains in strong contention to make his debut at the Barclays ATP World Tour Finals later in the year. 

“It was the knee,” said Thiem. “I had some problems with blisters, and maybe because of the compensation the knee started to hurt. I’m going to do an MRI now in the next couple of hours, and then I will have more information about it.

“From the end of the first set, beginning of the second set, it got worse and worse. No other choice.”

For only the second time all tournament long, Novak Djokovic played a full match on Sunday night at the US Open. The top seed showed the rest has only helped.

Djokovic moved into the quarter-finals in New York for the 10^th consecutive year, beating 21 year old Kyle Edmund 6-2, 6-1, 6-4 in Arthur Ashe Stadium. In the last eight, the defending champion will face ninth seed Jo-Wilfried Tsonga for the 22^nd time. The Serbian leads their FedEx ATP Head2Head series 15-6, including 11 of their past 12 meetings. Tsonga advanced to the quarter-finals with a four-set win against American Jack Sock.

“It feels great to play a match,” Djokovic said on court after the contest.

The two-time US Open champion hadn’t played a full match since 29 August, when he beat Pole Jerzy Janowicz 6-3, 5-7, 6-2, 6-1 in the first round. Czech left-hander Jiri Vesely withdrew before their second-round match because of inflammation to his left forearm. Djokovic was leading his third-round match against Mikhail Youzhny 4-2 before the Russian retired because of a back injury.

“This particular situation I [have] never had in my Grand Slam career,” Djokovic, a 14-year tour veteran, had said.

But he looked focused from the start against Edmund, who was playing in the fourth round of a Grand Slam championship for the first time. Djokovic gained two breaks and lost only two points on his first serve in the opener. The second set was more of the same, and after a little more than one hour, Djokovic held a two-set lead against Edmund, No. 84 in the Emirates ATP Rankings.

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But Edmund blasted his forehand more and made Djokovic worry in the third set. The Brit, who was playing in Arthur Ashe Stadium for the first time, fell behind an early break but marched back to lead 3-2 before Djokovic took the final set.

Djokovic’s left wrist, which he said had bothered him last month, looked fine but the 29 year old received treatment on his right arm for the second match of the tournament. Early on in the third set, a trainer massaged Djokovic’s right elbow. A trainer also had treated Djokovic’s right arm during his first-round match.

Bob Bryan and Mike Bryan have qualified for the Barclays ATP World Tour Finals, to be held at The O2 in London from 13-20 November, as a result of reaching the US Open quarter-finals on Sunday. The American twins, who has captured the prestigious season finale crown on four occasions, join Pierre-Hugues Herbert and Nicolas Mahut as the second team to book their spot.

The five-time former US Open titlists moved a step closer to their 17th Grand Slam championship by beating Spaniards Fernando Verdasco and David Marrero 2-6, 6-3, 7-5. They won the US Open in 2005, 2008, 2010, 2012 and 2014. Now into their 11th US Open quarter-final, the third-seeded Bryans will compete against eighth-seeded Spaniards Feliciano Lopez and Marc Lopez or Brazilians Thomaz Bellucci and Marcelo Demonliner.

Aussie Chris Guccione and Brazilian Andre Sa also moved into the last eight on Sunday in New York. Guccione/Sa prevailed against Spaniard Nicolas Almagro and Dominican Victor Estrella Burgos 7-6(2), 6-2.

Spaniards Pablo Carreno Busta and Guillermo Garcia-Lopez knocked out Americans Nicholas Monroe and Donald Young 4-6, 7-6(4), 6-3. The Spaniards will face No. 12 seeds Lukasz Kubot of Poland and Alexander Peya of Austria in the quarter-finals. Kubot/Peya received a walkover when Brit Daniel Evans and Aussie Nick Kyrgios withdrew.

Lucas Pouille uncorked an unplayable forehand down the line, his 59th winner of the match, to see off No. 4 seed Rafael Nadal 6-1, 2-6, 6-4, 3-6, 7-6(6) in the fourth round of the US Open on Sunday. The 22-year-old Frenchman, who collapsed to the ground after his shot landed just inside the sideline, reached the quarter-finals of a Grand Slam event for the second time in a row, and joined countrymen Jo-Wilfried Tsonga and Gael Monfils in the last eight. France had not had a trio of male players reach the quarter-finals of a major tournament since Roland Garros in 1947.

“For me, because I worked very hard, I’m feeling very confident, that’s why I’m here,” Pouille said. “For Jo and Gael it’s the same. They’re unbelievable players. They are at this level for many years now.”

Pouille will face Monfils in the US Open quarter-final and try to reach the last four of a Grand Slam for the first time. “He’s in very good form. He has won so many matches for the last two months. He’s very confident. He hasn’t lost a set, so I know it’s going to be hard,” Pouille said of Monfils. “But I’m playing well. I have good feelings on the court, so we’ll see. I think it’s going to be a tough match for me, but for him as well. It’s going to be interesting.”

No. 24 seed Pouille lost to Nadal in Monte-Carlo last year in the pair’s lone previous FedEx ATP Head2Head meeting, but the right-hander started the match with no signs of being intimidated by the legendary Spaniard, who won the US Open title in 2010 and 2013. Pouille was a model of controlled aggression from both wings, pushing Nadal deep into the backcourt with angled drives and approaching the net 63 times (38/63). Nadal, too, mustered his best all-court tennis. He fired 52 winners and won 35 of 48 trips to the net.

Four hours of play decided nothing, so the outcome needed to be decided by the first fifth-set tie-break played on Arthur Ashe Stadium this fortnight. Pouille, who played 19 out of a possible 20 sets this week, showed signs of mental fatigue, dumping a mid-court forehand into the net on the opening point.

However, the rising star righted the ship and was soon up 6/3. On the brink of losing, Nadal showed his resilience by winning the next three points, but also missed a short forehand put-away at 6/6, a shot he has made a living dispatching.

“A big mistake, yeah. But you are six-all in the tiebreak. I played the right point. I put [myself] in a position to have the winner and I had the mistake,” Nadal said. “The problem is arriving to six-all on the tiebreak of the fifth. I should be winning before.”

The rare misstep from Nadal allowed Pouille to put the finishing touch on a remarkable victory. Pouille has now won three consecutive five-set matches, and is No. 5 in the Under Pressure Leaders category of the ATP Stats Leaderboards, powered by the Infosys Information Platform.

“I think because mentally I’m stronger, physically I’m stronger, [that] gave me a lot of confidence before the match,” Pouille said. “I knew if I wanted to win that, it’s not going to be like three sets, 6-1, 6-2, 6-2. It would be long. So I was ready for it.”

Jo-Wilfried Tsonga ended American hopes at the US Open as he defeated last man standing, Jack Sock, 6-3, 6-3, 6-7(7), 6-2 in New York on Sunday.

The Frenchman had a match point in the third set but Sock saved it and looked to have the American crowd behind him heading into the pivotal fourth set. Tsonga broke the 23 year old twice in the final set to move into his second Grand Slam quarter-final of the season (Wimbledon, l. to Murray).

“It was really difficult because he played great in the third,” Tsonga said during his on-court interview with ESPN after the match. “I just tried to play my game in the fourth and that’s it. Stay focused on what I have to do.”

The Frenchman is looking to mount a late charge in the Emirates ATP Race To London and helped his cause by reaching the quarter-finals at Flushing Meadows for the second year in a row.

Tsonga started the US Open at 16^th in the year-to-date standings, just over 1000 points behind eighth-placed countryman Gael Monfils, who also advanced to the quarter-finals earlier with victory over Marcos Baghdatis.

View Emirates ATP Race To London

Tsonga fell in the last eight to Marin Cilic at the US Open last year and will look to reach his first Grand Slam semi-final since he made a run on home soil last year at Roland Garros (l. to Wawrinka).

The 31-year-old Tsonga controlled the contest with Sock during the first two sets, winning 85 per cent of his first-serve points (28/33) and hitting 28 winners to take a two-set lead. Sock rebounded in a packed Louis Armstrong Stadium, though, running around a Tsonga serve to hit a forehand winner and take the third set.

After the clean forehand, the Nebraska native, who was looking to reach his first career Grand Slam quarter-final, lifted his arms to try to rally the crowd. But Tsonga’s big-match experience paid off in the fourth as he did not face a break point in advancing.

The ninth seed goes on to face either World No. 1 and defending champion Novak Djokovic or #NextGen star Kyle Edmund. Asked on court if he’d like the two to endure a quick three-set match or a long five-set contest, Tsonga said, “Of course, a long five-set match. Really long. Really, really, really long,” he said in between laughs. “I’m in a quarter-final and now everything can happen, so I will give my best. I will fight for it, and we will see.”

Sock, No. 26 seed, was trying to become the first homegrown quarter-finalist in the US Open men’s draw since 2011, when Andy Roddick and John Isner reached the last eight.