Federer breakspublished at 20:39 Greenwich Mean Time 21 November 2015
*Federer 4-4 Wawrinka
Roger Federer is back to level pegging as Stan Wawrinka's radar gets a little wonky off the deck.
Image source, Getty ImagesSummary
Roger Federer beats Stan Wawrinka 7-5 6-3
Federer v Novak Djokovic in Sunday's final (18:00 GMT)
Djokovic beat Rafael Nadal 6-3 6-3
Federer breakspublished at 20:39 Greenwich Mean Time 21 November 2015
Image source, Getty ImagesTwo break points Federerpublished at 20:38 Greenwich Mean Time 21 November 2015
Federer 3-4 Wawrinka*
Stan Wawrinka plants a groundstroke wide and then duffs down a double fault and all of a sudden he has 15-40 and two break points to defend...
Get Involved: Baseline bust-upspublished at 20:38 Greenwich Mean Time 21 November 2015
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John McEnerney, external: McEnroe & Connors in 82, Jimbo walked the length of the court & got right in JohnMc's face. No love lost there only hatred.
JohnMc on JohnMc, who'd have thought it?
If we get an I Nastase on Ilie Nastase, we'll start getting suspicious...
Federer 3-4 Wawrinka*published at 20:37 Greenwich Mean Time 21 November 2015
Image source, Getty ImagesFederer delivers a solid service game to keep in touch.
After that little flurry of break opportunities earlier in the set, it has all gone a little quiet at the returner's end.
David Beckham is doing a double session by the way. The former England captain - who always makes the most of his Wimbledon Royal Box pass - has hung about for the evening session after watching Novak Djokovic beat Rafael Nadal this afternoon.
Postpublished at 20:34 Greenwich Mean Time 21 November 2015
Miles Maclagan
British tennis coach on Radio 5 live sports extra
Image source, AFPThat's a great hold after the break from Wawrinka. Nice and comfortable after dropping the first point.
*Federer 2-4 Wawrinkapublished at 20:33 Greenwich Mean Time 21 November 2015
Stan Wawrinka's serve has proved as slippery as an eel so far. Roger Federer is struggling to pin it down, chasing out wide and lunging back towards the tee as the barrage comes skidding his way.
A hold to 15 and the break backed up to open up some clear blue water on the scoreboard.
Wawrinka breakspublished at 20:29 Greenwich Mean Time 21 November 2015
Federer 2-3 Wawrinka*
Image source, AFPThe net cord clearly is a Wawrinka fan.
First it flicks a Wawrinka forehand up into Federer's face at the net and he cannot scrape back.
Then it diverts a Federer shot wide between the tramlines.
First blood to Stan.
Federer taken to deucepublished at 20:28 Greenwich Mean Time 21 November 2015
*Federer 2-2 Wawrinka
A little ripple of concern.
The sort you might hear if someone spilt their tea over the headmaster at a parents' evening.
Roger Federer has caused it. His double fault has given Stan Wawrinka 15-30.
He redeems the damage, but then yanks a forehand wide to offer up deuce.
*Federer 2-2 Wawrinkapublished at 20:26 Greenwich Mean Time 21 November 2015
Stan Wawrinka's forehand is full of socking power.
Another stroke out of the meaty part of the strings, stretches Federer out of shape just when the world number three sniffs a chance at 15-30.
A blurring ace seals the deal for Stan.
A hushed atmosphere at the O2 Arena. The crowd are into every point, savouring them like a selection box.
Federer holdspublished at 20:22 Greenwich Mean Time 21 November 2015
Federer 2-1 Wawrinka*
Image source, Rex FeaturesRoger Federer gives Stan Wawrinka the slip, lulling his man into a couple of errors to wriggle off the hook.
Federer taken to deucepublished at 20:20 Greenwich Mean Time 21 November 2015
*Federer 1-1 Wawrinka
After 11 points on serve, Stan Wawrinka finally brings the tee-off dictatorship to an end with a lovely, short backhand punch down the line for 40-15.
This rebellion has caught alight a bit. A forehand winner and Federer a smidge wide and out of nowhere we have deuce.
Swiss timingpublished at 20:18 Greenwich Mean Time 21 November 2015
Image source, Piers Newbery*Federer 1-1 Wawrinkapublished at 20:18 Greenwich Mean Time 21 November 2015
Image source, EPAAnd Stan Wawrinka picks that gauntlet right up.
A hold to love of his own with his serve delivering arcing exocets out wide and down the middle.
Game on.
Federer 1-0 Wawrinka*published at 20:16 Greenwich Mean Time 21 November 2015
Roger Federer doesn't do snarling. Far too messy for the man himself. So he lets his tennis do the aggression.
A hold to love, with three out of the four points won at the net.
Slap! That is the sound of a gauntlet being laid down.
*Federer 0-0 Wawrinkapublished at 20:13 Greenwich Mean Time 21 November 2015
The players return to their courtside seating to sort out some bottles, wipe down some brows and stretch off some final muscles.
Federer to serve...
Image source, Rex FeaturesSprint finishpublished at 20:12 Greenwich Mean Time 21 November 2015
British athlete's courtside view
Image source, Dina Asher-SmithGet Involvedpublished at 20:10 Greenwich Mean Time 21 November 2015
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In honour of last November's rather public misunderstanding between Mirka Federer and Stan Wawrinka, we are looking for your favourite on-court spats tonight.
David Nalbandian and foot-level advertising? Tim Henman and innocent ball girls? We've got video of them both in one convenient click.
Let us know via #bbctennis , externalon Twitter and the BBC Sport Facebook, external page.
BBC coveragepublished at 20:09 Greenwich Mean Time 21 November 2015
Federer v Wawrinka
BBC Radio 5 Live Sports ExtraThis match is live on BBC Radio 5 live sports extra. You can get across their coverage with a click at the top of this page on either the play icon or the live coverage tab.
Player out on courtpublished at 20:08 Greenwich Mean Time 21 November 2015
Federer v Wawrinka
The umpire attempts to steal the scene at the net introductions asking, like a boxing referee, for "a clean fight" and "no blows below the belt".
Federer, ever the diplomat, manages to raise a watery smile.
Postpublished at 20:05
Federer v Wawrinka
Piers Newbery
BBC Sport at the O2 Arena in London
Image source, Getty ImagesThe largest contingent of obviously partial supporters at this afternoon's semi-final were not Spanish or Serbian, but Swiss.
Such is their confidence in Federer, and more latterly Wawrinka, that it seems every sports fan in Switzerland block books the semi-finals and final at the O2 every year.
They might not have enjoyed what they saw this afternoon, with Djokovic looking imperious, but if he is to be stopped it will be a Swiss who does it.