Rafael Nadal’s 21-match unbeaten run ended on Friday when he lost to Dominic Thiem in the quarter-finals of the Mutua Madrid Open. It also brought to an end his 50 consecutive set wins, which is now an open era record after he surpassed John McEnroe’s 49 consecutive sets won on carpet in 1984.

The Spaniard’s loss in the last eight at Madrid will also see him drop back to number two in the ATP men’s singles ranking, when the rankings are revised on Monday, with Roger Federer set to take over at the top despite not playing a single event since March 24 when he lost in the second round at the Miami Open.

Nadal is defending 4,680 points during the clay season and had to win in Madrid to maintain his position at the top. But he came up short against Thiem on Friday, who was also the last person to beat him on clay at the Italian Open in 2017 which occurred 357 days back.

The Austrian like the Spaniard favors clay and has won seven of his nine titles on the red dirt. Thiem was billed as one of Nadal’s main challengers coming into the clay court season, but their first meeting was a whitewash as the latter won 6-0, 6-2 in the quarter-finals of the Monte Carlo Masters.

Rafael Nadal Dominic Thiem (L) is the only player to beat Rafael Nadal on clay since the start of the 2017 season. In this picture, Dominic Thiem of Austria shakes hands with Rafael Nadal of Spain after his straight sets victory during their quarterfinal match on day seven of Mutua Madrid Open at the Caja Magica on May 11, 2018 in Madrid, Spain. Photo: Denis Doyle/Getty Images

The world number seven admitted he had to play an extraordinary match to overcome arguably the greatest ever player on clay and pointed to his attitude leading up to the match as one of the key factors that helped him prevail on Friday.

“I had to play an extraordinary match, and that's what I did," Thiem said after his win, as quoted on ATP’s official site. "It takes a really good match to beat Rafa on clay, but I think a very important thing was that I went in with the attitude that I can beat him. Obviously, two weeks ago in Monte-Carlo, he killed me love and two. It was very important I went into the match with a positive attitude, with an attitude to win.”

“I moved well [and] I was physically tough. But always against him, there are long rallies. You get out of breath. My groundstrokes were the best, they were very aggressive. I think I really hurt him with them… I didn't make too many stupid errors. That was important,” he added.

Thiem will face Kevin Anderson in the last four on Saturday after the South African tamed Dusan Lajovic in his quarter-final clash. The Austrian will have to break a six-match losing streak if he has to overcome the world number eight and make it to his second final of the 2018 season.

Nadal, meanwhile, was upset after losing to Thiem, but admitted the Austrian was better on the day. The Spaniard has been relentless since the clay court season began, not losing a single set thus far on his way to two titles in Monte Carlo and Barcelona.

“Of course, I'm upset,” Nadal said. “I tried to come back. I tried to do it a couple of times, but I wasn’t good enough today. He was better than me today, that's the end of the story. Some days you don't play as well as you'd like to play. Also, when that happens, it's because your opponent is doing really well. I just want to congratulate him, that's all.”

The 31-year-old will return to action at the Italian Open in Rome that begins on Monday and it will present him an opportunity to return to the top of the rankings yet again. Nadal lost in the quarter-finals in Rome last season and if he wins the event this year, he will again overtake Federer before the start of the French Open later in the month.