Miami - Roger Federer described himself as "incredibly lucky" to have beaten Tomas Berdych in the Miami Open quarter-finals, but credited his 6-2, 3-6, 7-6 (8/6) victory on Thursday to thinking young.
Federer trailed 6-4 in the third set tie-breaker but fought back and won the quarter-final match when Berdych double-faulted at the decisive moment.
"I was like, 'Wow, double fault. Are you kidding me? You're too kind, Tomas. Why? How do I deserve this one?'" Federer said.
"I don't feel like I deserved it that much, a double fault at that moment. I guess he was playing on the edge. I got incredibly lucky. Could have gone either way."
Recalling Berdych's 2010 victory over him in the fourth round, Federer said, "I felt like maybe this one I should have lost and maybe I should have won the one against him here in the night session years ago."
The 35-year-old Swiss star was asked whether he thought experience helped him deal with the pressure of a tight tie-break decider and replied that it could be a double-edged sword.
"I guess you get better over time handling pressure," Federer said. "Then you have to be careful, I think, as you grow older, not to play too conservative when it matters. You start playing percentages way too much when you get older because you've seen too many times what can happen.
"Sometimes when you have that young mind you just go for it, and that's when actually great things do happen. You've just got to play committed tennis.
"So for me, it's always a balance between playing the percentages yet play free and sort of young in the mind."
Federer's victory kept alive the chance of yet another encounter with his long-time rival Rafael Nadal in Sunday's final, one Federer said he would relish.
"It would be very cool," Federer said. "They have been talking about it since the beginning of the tournament, which is nice. I'm happy we both made it this far. I definitely got super lucky today to be in the position that I'm in today, the semis.
"I would love it. It would be like a throwback to 2005, the finals we played - 2004 we played the first time ever against each other here in Miami. So that would be cool, to have that going.
"Plus Rafa going for his first Miami Open. I think that would be cool, too."