Everyone in Delray Beach was rooting for Juan Martin del Potro, even his next opponent.

“I was really happy for him to come back,” said Jeremy Chardy, whom the Argentine will meet in the quarter-finals of the Delray Beach Open. “For a tennis player, the worst is to be injured. [His comeback] is great for the fans too. We need players like him on the tour.”

Del Potro downed Aussie John-Patrick Smith 6-4 6-4 during Thursday’s night session in 77 minutes to set up a third meeting against Chardy (1-1), who eased past American Noah Rubin 6-4, 6-2.

“Physically I felt good,” del Potro said after his match. “But I was playing too many slices. It’s not my game. If I improve my backhand, I will once again be the Tower of Tandil.

“I am so happy to be here, playing in front of my fans. If I can play better, next year I will be back for sure.”

Chardy will be hard-pressed to handle del Potro’s power, but he was glad to see his close friend continue his comeback bid.

“I know [del Potro] really well,” Chardy said. “He’s one year younger than me so we’ve known each other since we were kids. He’s a good friend of mine. We had a lot of fun in juniors together. We never missed a Players Party [back then].

Tim Smyczek was down a set and a break to fellow American Donald Young, but rallied 1-6, 7-6(2), 6-2 to reach his second ATP World Tour quarter-final (2011 San Jose).

“I was trying to figure out how to disrupt what he was doing,” Smyczek said. “My game plan wasn’t bothering him so I had to do something different. I stopped being so offensive. [Young] does very well when he’s under pressure so I had to turn the tables a bit.

“Because we’ve played each other so often in the past, I had to do some things which weren’t my forte. Same for him, which was interesting. I am happy I fought my way through.”

His standing as the King of Clay is undisputed, but on Thursday top seed Rafael Nadal had to grind his way past another of the ATP World Tour’s most dominant clay-courters, Nicolas Almagro, at the Rio Open. In the battle of the Spaniards, Nadal steadied to hold off the former World No. 9 6-3, 7-5 to reach the quarter-finals of the tournament he won in 2014.

Nadal brought a dominant 347-31 record on clay into his second-round match – clearly the best among active players – while Almagro arrived with a 262-129 mark, the third best on tour. Almagro, though, would have to win just his second FedEx ATP Head2Head clash with his 29-year-old countryman, having won just four of the 36 sets played between the two in 14 previous encounters.

Nadal drew first blood, breaking for 3-1 in the opening set. He recovered from 0-40 while serving for the set to take it after 43 minutes. In the second set, the World No. 5 in the Emirates ATP Rankings had the chance to serve out the match after breaking to love for 5-4.

With the finish line in sight, however, Nadal wavered. He dropped serve before breaking Almagro again in what was the fifth straight break of serve between them. Serving for the match for a second time, Nadal made no mistake. He closed it out on his first match point in one hour and 41 minutes to book a rematch of his 2014 final against Ukraine’s Alexandr Dolgopolov.

Third seeds Treat Huey and Max Mirnyi are through to the Delray Beach Open semi-finals after a 6-3, 6-4 triumph over Australians Chris Guccione and Bernard Tomic. The Filipino-Belarusian duo hit seven aces between them, winning 80 per cent of first-serve points. They will meet unseeded pair Oliver Marach and Fabrice Martin for a place in the final.

At the Rio Open, it was a good day for the home tandems. Top seeds Marcelo Melo and Bruno Soares won an all-Brazilian clash with Fabiano De Paula and Orlando Luz 6-2, 6-3 to launch their campaign, while wild cards Rogerio Dutra Silva and Joao Souza landed a narrow 2-6, 7-6(3), 10-8 first round win over Guillermo Duran and Philipp Oswald.

In Marseille, second seeds Mate Pavic and Michael Venus advanced to the semi-finals with a 2-6, 6-2, 10-7 win over Mateusz Kowlczyk and Andreas Siljestrom. Pavic and Venus won two of five break points in the one-hour, six-minute match. They will meet unseeded Aliasandr Bury and Igor Zelenay for a place in the final.

Nick Kyrgios and Teymuraz Gabashvili had a 6-3, 6-4 result over Marin Draganja and Julian Knowle in little more than an hour. They will take on Jonathan Erlich and Colin Fleming in an all-unseeded semi-final. Erlich and Fleming scraped past Robin Haase and Aisam-Ul-Haq Qureshi 6-3, 3-6, 11-9.

David Ferrer overcame a first-set hiccup to down countryman Albert Ramos-Vinolas 4-6, 6-1, 6-4 in the second round of the Rio Open on Thursday. Looming in the quarter-finals will be an in-form Dominic Thiem, who won the Buenos Aires title on clay less than a week ago.

Ferrer came into the match with a commanding 5-0 advantage in his FedEx ATP Head2Head rivalry against Ramos-Vinolas, but faltered in his opening service game en route to dropping the first set in 51 minutes. The tenacious Ferrer righted the ship, only losing serve once more in the next two sets to reach his fourth ATP World Tour quarter-final of the year.

Guido Pella lost just eight points in the second set of a 6-4, 6-0 win over Santiago Giraldo. The Argentine secured the win in 80 minutes and will face Daniel Gimeno-Traver in his second ATP World Tour quarter-final appearance (2013 Dusseldorf, l. to Monaco). Pella had saved three match points in the first round against John Isner.

In the evening session, top seed Rafael Nadal will attempt to record his 14^th win in 15 meetings against Nicolas Almagro, last week’s finalist in Buenos Aires.

Eighth seed Benoit Paire will meet his good friend, top seed Stan Wawrinka, on Friday for a place in the semi-finals at the Open 13 Provence. Wawrinka leads Paire 6-1 in their FedEx ATP Head2Head series, including victory last month in Chennai. Paire hit 10 aces past fellow Frenchman Vincent Millot, a qualifier, in a 6-3, 1-6, 6-3 win over one hour and 36 minutes on Thursday.

Andrey Kuznetsov, who turns 25 on Monday, will hope to improve on his 0-5 record in ATP World Tour quarter-finals when he takes on four seed and 2011 finalist Marin Cilic. Kuznetsov moved into the last eight by beating wild card Quentin Halys 6-0, 6-4 in 56 minutes.

Nick Kyrgios, who is playing in his second tournament of the year, struck 17 aces past Teymuraz Gabashvili in a 6-4, 6-4 victory over 72 minutes. He now awaits the winner of third seed Richard Gasquet or Ernests Gulbis, who play during the evening session. Earlier this month, Gasquet won his 13th ATP World Tour title at Montpellier (d. Mathieu).

Second seed and 2013 runner-up Tomas Berdych plays wild card Alexander Zverev to close out play on day four.