Roger Federer expects to take "one hell of a boost" having battled back from two sets down to overcome Marin Cilic 6-7 (4-7) 4-6 6-3 7-6 (11-9) 6-3 in the Wimbledon quarter-finals without any fitness concerns.
The 17-time major winner underwent knee surgery earlier this year, while a back injury forced him to withdraw from the French Open in May.
His bid for a record-breaking Wimbledon title looked set to be dashed when Cilic stormed into a two-set lead on Centre Court on Wednesday, but the Swiss showed immense character to turn the match on its head.
And coming through without any physical issues has raised the 34-year-old's confidence ahead of a semi-final against Milos Raonic.
"My legs and back were there and serving was key, plus mentally this will give me a hell of a boost," Federer said in his post-match TV interview. "I am really ecstatic I was able to make it into the next round.
"I think the last three sets I played really good. It is really encouraging to see I was improving and I was able to sustain a really high level."
The Swiss is chasing a record-breaking eighth Wimbledon men's singles title, and he is delighted that ambition remains alive.
"A lot happened out there. It was nice to play in these conditions and against Marin. He is such a wonderful player and I knew I was in so much trouble in the third set and in the fourth," continued Federer.
"It was great fun. Marin is one of the nicest guys on the tour so I feel sorry for him, but for me the dream continues. I played super great at the end so I am very, very, pleased.
"You hope [you can still win at 2-0 down] but you don't know.
"It wasn't going well for me so I just tried to stay in the match and hope for his level to drop and get a bit lucky and that is what happened."