Federer said on Wednesday that he was fist-pumping and high-fiving with his wife, Mirka, during Wawrinka's epic five-set win over defending champion Novak Djokovic, which earned him a first Grand Slam semifinal.
But he said he couldn't even contemplate playing his friend for the trophy ahead of the semifinals, where he will face Rafael Nadal and Wawrinka is playing Tomas Berdych.
"The moment you start thinking about that we're taking the same flight home," Federer said.
"Look, I'm worried about my match clearly, but I'll definitely watch his first," he said.
"Hopefully he can make it — then he can put the pressure on me that way."
Federer, who beat Andy Murray to reach the semifinals, admitted he wasn't "sitting there all quiet" during Wawrinka's win over Djokovic late on Tuesday.
"At the end I was standing up, hands in the air like him (Wawrinka)," he said.
Wawrinka will play Berdych on Thursday, a day before Federer's showdown with Nadal.