PARIS — Roger Federer came through his first serious test on his return to the French Open as he subdued some fierce Stan Wawrinka resistance to reach the French Open semi-finals on Tuesday.

Wawrinka beat fellow Swiss Federer at the same stage four years ago on his way to winning the title, but this time came up just short as Federer won 7-6(4) 4-6 7-6(5) 6-4.

Federer, 37, is the oldest man to reach the French Open semi-finals since Pancho Gonzales got there aged 40 in 1968 but will need to find a way to beat French Open nemesis Rafael Nadal if his quest for a second title in Paris is to continue.

They will meet on Friday for the 39th time with Nadal having won all of their previous five French Open duels.

Federer, who missed the 2016 French Open because of injury then the 2017 and 2018 editions to concentrate on Wimbledon, has played like he had never been away.

He cruised through his opening four rounds without dropping a set but knew a rejuvenated Wawrinka, approaching his best again after knee surgery in 2017, would be a dangerous beast.

So it proved as "Stanimal" stood toe-to-toe with his friend and rival for three hours 35 minutes of sublime action in front of a captivated Court Suzanne Lenglen crowd.

Even after he dropped serve after a cloudburst in the fourth set to give Federer the chance to serve for the match at 5-4, Wawrinka, who must have been feeling the pace after a five-hour marathon against Stefanos Tsitsipas on Sunday, would not buckle.

In a tense final game Federer wasted one match point with a double-fault but clinched victory with a volley on his third to reach a record-extending 44th Grand Slam semi-final.

"Hmm, the next opponent is okay," Federer said on court. "He knows how to play on clay, unfortunately.

"But thinking back, what a pleasure to be back at Roland-Garros. If I came back on clay, it's also perhaps to play Rafa. Here it is. I have the match."

Federer failed to convert any of the four break points that came his way in a tight first set — a theme of the match with the usually lethal Swiss taking only two of his 18.

The 20-time Grand Slam champion is usually clinical in tiebreaks though and duly took the first set on a breaker.

Wawrinka was straight back at him though and broke serve with a clubbing forehand winner to lead 3-1.

Serving for the set, the 34-year-old Wawrinka frittered away a 40-0 lead but whipped away a forehand to convert his fourth set point.

He looked to be gaining the upper hand when Federer hit a limp volley into the net to lose serve in the seventh game of the third set but Federer responded to break back immediately with the help of some unforced errors.

The third-set tiebreak always looked like a "must win" for Wawrinka but it was Federer who dominated it.

Federer pressed hard at the start of the fourth as the sky darkened and thunder rumbled, but Wawrinka was still refusing to budge and held firm until 3-3 when rain intervened.

On the resumption Federer proved clinical to claim his 23rd victory in 26 meetings with Wawrinka.

"It was a good battle, a great battle. We both had some little opportunity," said Wawrinka.

"Even if I had the break in the third set, he came back quickly. Only a few points could have changed ... the match." — Reuters