French Open 2018: Rafael Nadal set to face friend Diego Schwartzman in Roland Garros quarter-final

While Nadal won in straight sets once again, Schwartzman needed nearly four hours to beat Kevin Anderson 1-6, 2-6, 7-5, 7-6, 6-2

Rafael Nadal progressed to the last eight in Paris (Getty Images)

Diego Schwartzman, who trained with Rafael Nadal at the world No 1’s academy in Majorca last month, will again be on the opposite side of the net when the two men meet here in the quarter-finals of the French Open on Wednesday.

“I'm never going to invite him again, because every time he comes, he comes out much better,” Nadal said with a smile after both men won their fourth-round matches here on Monday. “It’s always good to see him in the quarter-final because he’s a good friend, a good person. He’s a worker, and I am happy to see him having all this success.”

While Nadal won in straight sets once again, beating Germany’s Maximilian Marterer 6-3, 6-2, 7-6 to reach the quarter-finals for the 12th time, Schwartzman needed nearly four hours to beat Kevin Anderson 1-6, 2-6, 7-5, 7-6, 6-2.

This is the second time in the last three Grand Slam tournaments that 25-year-old Schwartzman has made the quarter-finals. Marin Cilic and Lucas Pouille were among his victims at last year’s US Open before he lost to Pablo Carreno Busta.

At 5ft 7in Schwartzman is the shortest player in the men’s top 100. He gave away more than a foot to the 6ft 8in Anderson, who seemed to be cruising to victory when he won 17 of the first 23 games.

Schwartzman dug in, however, and fought particularly hard in the third and fourth sets. Anderson was broken when he served for the match at 5-4 in the third set and again two games later to give Schwartzman a foothold in the match. The Argentinian won the tie-break at the end of the fourth set 7-0 and went on to win the fifth set with something to spare.

The world No 12 seemed to become especially fired up after he complained to the umpire about shouting from people in Anderson’s player box.

“I was a little bit upset because in the beginning of the match I didn’t expect the first two sets,” Schwartzman said. “I was just trying to take something to stay on the court. Maybe that just helped me to be focused.”

Diego Schwartzman celebrates knocking out Kevin Anderson (Getty Images)

Nadal has beaten Schwartzman in all five of their previous meetings and dropped only one set in the process, in the fourth round at this year’s Australian Open. The Spaniard also beat him on clay in Madrid last month but said he would not underestimate the size of his task.

“He’s No 12 in the world,” Nadal said. “It’s a match against one of the best players of the world today, so you expect a very tough match and you need to be ready to accept that it’s going to be a tough match and fight for it.I know what I have to do, but it’s tough to make that happen, because he’s so good.”

Nadal, who won his 10th French Open here last year without losing a set, has now won 37 completed sets in a row at Roland Garros. If he wins his next four he will equal Bjorn Borg’s all-time record.

Asked if he felt he had yet to face a major test here, Nadal said: “My big test is every day. Today was an important test. I am in the quarter-finals. The biggest test now is the next round.I go day by day and I am not worried about whether I have had a test or not.

“I just worry about trying to be at 100 per cent for the next day that I have to play. That’s my goal. And I know if I make that happen, if I’m able to play with my highest intensity and with the right level, it will always be a tough match, but I really believe that I can have my chances to keep going.

“It’s like that every day. You go on court, you can win, you can lose. That’s the only thing that you need to be ready for.”

Having celebrated his 32nd birthday on Sunday, Nadal was asked if he was feeling his age. “I don't feel old, but I am 32, and I’ve been around here since 2003, so that’s a lot of years,” he said.“I started very young. But I feel happy to be here. I am enjoying being on the tour day by day and I hope to keep doing this for a while.”

The quarter-final line-up was completed by Cilic and Juan Martin del Potro, who won their fourth-round matches in contrasting styles. Cilic was kept on court for three hours and 37 minutes by Fabio Fognini before winning 6-4, 6-1, 3-6, 6-7, 6-3.

Fognini appeared to be in trouble when he was treated for an ankle problem in the second set, but the Italian responded admirably to take the match into a decider. Cilic made his crucial break in the seventh game of the fifth set and then served out for his victory.

Del Potro, a semi-finalist here in 2009, beat John Isner 6-4, 6-4, 6-4 in a battle between two of the game’s biggest servers. The Argentinian held serve throughout and won each set with a single break. “We both played good tennis today,” Del Potro said afterwards. “I’m having great days in Paris and I'd like to stay a few more days.”