Leon Smith
GB Davis Cup captain on BBC Radio 5 live sports extra

"Like most people who know Andy Murray well, I felt for him last night. But it's been a terrific end of year for Andy, to win that number of matches in the last five or six weeks shows you how far he's come. It's taken its toll on him, but it sets him up to have a good think in pre-season on what he needs to improve on. He does it most years - he goes away, comes back a better player, and he can look forward to 2015 now."

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To photobomb or not photobomb? It's a modern-day dilemma. I guess if you're a former Wimbledon champion you can get away with it. Marin Cilic's coach Goran Ivanisevic gets in on the act while the Tour Finals judges try to take a group photo.

It's been an incredible year for US Open champion Cilic but he hasn't been at his best in north Greenwich. The Croat has lost his two group matches, suffering a 6-3 6-1 defeat by Tomas Berdych and a 6-1 6-1 loss to Novak Djokovic. Incredibly, he has had his serve broken 10 times during this tournament. Will Wawrinka make him suffer some more before the season ends?

Wawrinka and Cilic are at the net for the coin toss, Wawrinka continuing with those lunges. Never has a man's muscles been so prepared for battle. Anyway... it's Wawrinka who will serve first after the US Open champion decides to receive.

Russell Fuller
BBC tennis correspondent on Radio 5 live sports extra

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"Tomorrow evening's semi-final will be Roger Federer against, probably, Stan Wawrinka. There have been so many one-sided matches this week, that we should reserve judgement at least for the first 10 minutes - as Wawrinka could go through if he starts well."

Last-minute stretching for Wawrinka, who is lunging in the corridor before the players are called to make their way to the court.

Cilic leads the pair out and, as he approaches the arena, he can probably hear the crowd clap along to the sound of the beating heart which is booming out of the sound system.

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Roger Federer awaits in the second semi-final. But, in an attempt to clear a few things up, here is who needs to do what:

• If Wawrinka wins - then he qualifies for the semi-finals.

• If Cilic wins in two sets - the runner-up in the group is determined by the percentage of games won.

• If Cilic wins in three sets - Wawrinka qualifies for the semi-finals.

All Stan needs to do is to take this match to a third set. In fact, the percentages mean that if Cilic wins in two sets but Wawrinka wins three or more games along the way, Wawrinka goes through. Confused? No? Good.

Wawrinka is within touching distance of the semi-finals. He's so so close. The Australian Open champion merely needs to win three games against Cilic to set up an all-Swiss semi-final with Roger Federer, although had Wawrinka watched his friend's 6-0 6-1 thrashing of Andy Murray last night he may prefer to enjoy London's Christmas markets on Saturday rather than play a compatriot who is in eye-wateringly good form.

It's time to start the final countdown for the final showdown. After 11 matches, 23 sets and 187 games, the final group match is upon us.

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Are we too late for fireworks or too early? Stanislas Wawrinka versus Marin Cilic isn't ordinarily a match which would light up London's skies, but in a few hours the semi-final line-up for the ATP World Tour Finals will be decided and that is reason enough for pyrotechnics if you ask me. And it's Friday.