Roger Federer is wary of the threat posed by a revitalised Marat Safin as the Swiss star continues his quest for a record-equalling sixth straight Wimbledon title on Centre Court on Friday.
Former world No.1 Safin has made a mockery of his current lowly ranking of 75 to storm into his first All England Club semi-final at the ninth attempt, and Federer knows the two-time grand slam champion is no pushover.
Calling Safin's current ranking 'ridiculous', Federer added: "He's finally showing again what he can do. It's just quite surprising he's doing it here at Wimbledon, because he used to dislike playing on this surface."
"Last year I wasn't happy to see Safin in my draw. I'm never happy and he probably knows that. He's just been disappointed with the way he's been playing lately, but hopefully he's got a second thing going."
Surly Safin has beaten Federer just twice in their 10 previous meetings and did his best to play down his chances of triumphing for a third time after his four-set quarter-final win over Feliciano Lopez.
But Safin is clearly beginning to relish his two weeks in SW19 and showed glimpses in the fourth set against Lopez of the hard-hitting accuracy which once briefly made him the man to beat.
"I have had to deal with the things I have had in my life, a lot of injuries. I'm tired of making comebacks every year. It's annoying but that's my career. I'm managing to enjoy it," he said.
"Throughout the week I've had some tough matches and a lot of pressure. I think I've been playing great tennis and very close to my best tennis. But just a little bit more would be great."
However the smart money remains on a third consecutive final between Federer and Rafael Nadal, who bludgeoned Andy Murray to last-eight defeat and starts an unbackable favourite in his semi-final clash.
Nadal insists his best is yet to come as he prepares to push Federer further than last year's five-set final epic, in which the Spaniard held four break points in the final set before finally folding to defeat.
"You can improve the serve. You can improve everything. If Federer can improve, I can improve a lot," said Nadal.
"Last year was close. Only one more point and I probably would have had the trophy in my home. It was disappointing to have another plate."
"I don't know if this year I'm going to have more chances to win the title. I have to play well if I want to win this tournament. I am playing well, but I don't know if it is going to be enough."