Nadal claimed his 49th and 50th consecutive sets won on clay, eclipsing McEnroe's record of 49 straight single-surface set victories, which he accomplished in 1984 on carpet.
Thiem was utterly sensational as he powered his way to a 7-5 6-3 quarter-final victory in front of a shocked crowd at the Caja Magica. "All these things, probably after I finish my career will be the time to think about it", Nadal was quoted as saying on the ATP World Tour's Web site. But I've done it. "Let's not talk about that any more and let's continue on what we have ahead which is what I am concerned about". Thiem has won five of his last eight semifinal appearances.
He will now face South Africa's Kevin Anderson, who overcame Philipp Kohlschreiber.
'Having said this, I think I placed myself in a good position more or less. "But I have to keep working on them and pray that.and hope that my game will get stronger". "Right now I'm quite calm".
While del Potro faltered against Serbian qualifier Dusan Lajovic, Sharapova was beaten by Kiki Bertens of the Netherlands on Thursday.
Pliskova is now the highest seeded player left in the women's tournament after both No. 2 Caroline Wozniacki and third-seeded Garbine Muguruza lost Wednesday.
Pliskova's 6-4, 6-3 win means she will play either two-time Wimbledon champion Petra Kvitova or the talented Russian Daria Kasatkina for a place in the final on Saturday.
Manchester United seal second spot with West Ham draw
There was a more subdued atmosphere from the home fans at the end of another deeply frustrating campaign for the Hammers. Marko Arnautovic again looks in the mood for the east Londoners.
"It will be a very tough match to play but it is a very good opportunity to play against one of the best players of the world". "I feel awesome since in the last six matches I lost to her".
Sharapova looks unlikely to be seeded on her return to the French Open where she has won the title twice. "He was better than me today".
"I go back to the drawing board and start over again".
Earlier, former world number one Novak Djokovic crashed out of the tournament after going down against British player Kyle Edmund in the second round.
Edmund will next face Canadian teenager Denis Shapovalov, who achieved a 6-4 6-4 win over compatriot Milos Raonic.
Second seed Alexander Zverev beat Argentina's Leonardo Mayer and will now do battle with John Isner.