Roger Federer’s semi-final will test his intelligence as much as his reactions as he takes on Tommy Haas, the 31-year-old German who is basking in the warmth of an unexpected Indian summer. The German has come here for once injury-free and he has lit up the championships by mixing classic serve-and-volley with wit and innovation from the back of the court. Haas let Federer off the hook when they met at this year’s French Open, letting the Swiss come back from two sets and a break-point down, and with that heroic tussle still fresh in everyone’s mind, their meeting on Friday will have added piquancy.

Haas is a player who looks better than ever here. After saving two match points against Marin Cilic in the third round, Haas has gone from strength to strength and reached the semis with a cool victory over world number four Novak Djokovic on Wednesday.

“Against Tommy I have to play a good match from the start,” Federer said. “As we saw in Paris, it was brutal.”