Postpublished at 15:19 British Summer Time 4 June 2019
*Wawrinka 6-7 (4-7) 6-4 4-3 Federer
Stan Wawrinka flops a forehand long.
Two break back points in Roger Federer's favour...
Roger Federer beats Stan Wawrinka to set up semi-final against Rafael Nadal
Federer overcomes Swiss compatriot 7-6 (7-4) 4-6 7-6 (7-5) 6-4 at Roland Garros
Britain's Johanna Konta beats American Sloane Stephens 6-1 6-4 to reach semi-finals
Konta first GB woman since Jo Durie in 1983 to make last four at Roland Garros
Rafael Nadal beats Kei Nishikori 6-1 6-1 6-3 in other men's quarter-final on Tuesday
Mike Henson and Alex Bysouth
*Wawrinka 6-7 (4-7) 6-4 4-3 Federer
Stan Wawrinka flops a forehand long.
Two break back points in Roger Federer's favour...
*Wawrinka 6-7 (4-7) 6-4 4-3 Federer
All in the eyes.
Roger Federer glances one way and whips a forehand winner the other, drawing Stan Wawrinka out of the way with his glance.
15-30.
*Wawrinka 6-7 (4-7) 6-4 4-3 Federer
He only needs one!
Roger Federer scuttles towards the net, but cannot pick up a dipping return from Stan Wawrinka and jabs it into the tape.
It's Wawrinka who takes the advantage in the third set.
*denotes next server.
Wawrinka 6-7 (4-7) 6-4 3-3 Federer*
Federer drives a backhand into the guts of the net. That's two break points for Wawrinka...
Wawrinka 6-7 (4-7) 6-4 3-3 Federer*
Wowsa. Roger Federer barely saw that pass him... magnificent backhand return from Stan Wawrinka that whistles beyond his fellow Swiss en route to the net. 0-30.
Wawrinka 6-7 (4-7) 6-4 3-3 Federer*
Whistles on Suzanne-Lenglen... the supporters already there aren't impressed by the late-comers, and neither are the players. If you've got a ticket, where have you been?!
Stan Wawrinka thumps his way to 40-0 with his seventh ace of the day and then the 2015 champion shows off his softer side, deftly clipping a drop shot over the tape to hold to love.
*Wawrinka 6-7 (4-7) 6-4 2-3 Federer
Roger Federer, sporting England Euro '96 grey, fist pumps and screams "come on" after an enduring rally completes the comeback from 0-30 down to 40-30 and then he holds, puffing out his chest and wiping away the sweat gathering on his brow.
Who'd call this one?!
Wawrinka 6-7 (4-7) 6-4 2-2 Federer*
And now Wawrinka is cooking. He edges his way to 0-30 on the Federer serve.
Wawrinka 6-7 (4-7) 6-4 2-2 Federer*
Superb from Stan Wawrinka. As sweet as you like on his forehand side, drifting out right and flinging a winner into the opposite corner.
*denotes next server.
*Wawrinka 6-7 (4-7) 6-4 1-2 Federer
Saved from Stan! Wawrinka finds a huge serve when he needs it most.
*Wawrinka 6-7 (4-7) 6-4 1-2 Federer
Now Roger Federer does get his break point chance...
*Wawrinka 6-7 (4-7) 6-4 1-2 Federer
Line and length from Roger Federer, nonchalantly picking out a winner that kisses the baseline on its way through. The world number three senses a break, but Stan Wawrinka squeaks through the gears to make it 30-30.
*Wawrinka 6-7 (4-7) 6-4 1-2 Federer
A hold to love for Roger Federer. Fizzing down successive aces in an almost irritated fashion.
Wawrinka 6-7 (4-7) 6-4 1-1 Federer*
Stan Wawrinka delves into his armoury and pulls out a string-snapper of a serve to hold.
*denotes next server.
Jonathan Jurejko
BBC Sport at Roland Garros
If you're at Roland Garros but can't get on Lenglen, watching Wawrinka and Federer on the big screen on the side of Court One is a popular alternative.
Next year things will be different around here, with the Bullring - as it is affectionately known - being torn down at the end of the tournament.
This area will then be opened up and able to house more fans in a viewing park-style area.
*Wawrinka 6-7 (4-7) 6-4 0-1 Federer
Roger Federer skips across the clay like a NBA star sensing a slam dunk to hammer home a short ball from Stan Wawrinka, and then shows the precision of a major-winning golfer to level at 30-30.
*Wawrinka 6-7 (4-7) 6-4 0-1 Federer
Brilliant!
From both players... Stan Wawrinka unloading with everything he's got to try and beat Roger Federer at the net, but the veteran Swiss lands strings on a volley to plant it out of Wawrinka's reach.
He holds.
Wawrinka 6-7 (4-7) 6-4 0-0 Federer*
Another uncharacteristic error from Roger Federer, whipping a backhand from mid-court into the net tape. He sweeps a strand of hair that's slipped from his headband away and gets set for deuce number three..
Wawrinka 6-7 (4-7) 6-4 0-0 Federer*
Inch-perfect from the 20-time Grand Slam champ, frustratingly out of reach near the tramline for his Swiss counterpart. But Roger Federer can't quite close out. Deuce.
Wawrinka 6-7 (4-7) 6-4 0-0 *Federer
Strap in folks, order a glass of your favourite from the trolley and put on your comfy socks - we are in for the long haul.
Stan Wawrinka puts a lid on those finishline wobbles and claims the second set to cheers from Court Suzanne Lenglen.
One hour and 36 minutes on the clock.