Rafael Nadal maybe playing his best tennis on the grass of SW19, but the Spaniard is not expecting an easy time against Rainer Schuettler.
The 32-year-old Schuettler came through a gruelling quarter-final tie against Arnaud Clement, with the match spread over two days and lasting five hours and 12 minutes - the joint second longest tie in Wimbledon history.
And although Nadal wrapped up victory in his one-side last-eight match against Andy Murray in double quick time on Wednesday, he knows that Schuettler will pose a tough test.
Schuettler failed to qualify for Wimbledon last season, while in 2005 and 2006 he failed to make it past the first round.
But world No.2 Nadal said: "I'm going to have a difficult match against Schuettler because he is playing well.
"If he is the semi-finals, it is because he is playing very well. I don't want to think about the final. Not yet.
"I have to play very well if I want to win this tournament. I am playing well, but I don't know if it is enough. I hope so."

Fleming - ATP had vested interest
Davydenko masters Nadal
Davydenko v Nadal
Nadal v Lopez
Davydenko v Djokovic
Djokovic happy with straight sets victory
Nadal v Blake - Nadal
Del Potro wins US Open
Has American's confession to lieing about his drug use tarnished his legacy? It's Your View...
Andy Roddick is the sixth player to qualify for the ATP World Tour Finals, which will be live on Sky Sports.
Read what Sky Sports' experts and bloggers have been talking about over the last seven days in sport...