The Swiss star ousted his compatriot 7-6, 4-6, 7-6, 6-4 to reach the final four at Roland Garros for the first time since 2012.
Roger Federer now takes on long-time rival and 11-time French Open champion Rafael Nadalin a hotly-anticipated semi-final clash.
At the age of 37, Federer is going for his 21st Grand Slam and only his second ever major title on clay.
Despite his age, the ATP Tour veteran remains one of the greatest players on the tennis circuit having recently taken his number of titles to 101 with wins in Dubai and Miami.
But naturally Federer is coming to the end of his career amid constant speculation as to when he will finally decide to retire.
For now, the 20-time Grand Slam champion is still going strong and appears likely to continue on tour next year.
Federer, however, had to field a question asking if he was finding it harder to deal with the mental toils of tennis as he ages.
He only converted two of his 18 break points as he found it difficult to see off his countryman Wawrinka.
And one reporter inquired as to whether that was because, with age, he was finding it tougher to cope with the mental pressure as Mats Wilander had as a player.
The journalist asked: “Roger you had a lot of break points that you found it difficult to convert on today and you had a couple of double faults I think in your last game. I was talking earlier to Mats Wilander who said actually as you get older the pressure does become more difficult to manage. I wonder if for you whether closing things out now is becoming a little tougher?”
But in eight simple words, Federer shut down such a suggestion as reports broke out into laughter.
“No, it’s not,” Federer said simply with a wry smile.
He then sparked further giggling as he added: “And send Mats my best!”
The journalist declared that Wilander wasn’t necessarily saying Federer found it more difficult as he sought to draw more of an answer from Federer.
But the world No 3 just rebutted: “I’m not taking it personal but still send him my best regards.”
Federer now turns his attentions to his 39th career meeting with Nadal, which will be his first since the Shanghai Masters in 2017.
The pair were due to meet in the semi-finals of the Indian Wells Masters back in March but Nadal had to withdraw due to injury, giving Federer a walkover win before he lost to Dominic Thiem in the final.