Right on cue, here comes Novak into the arena amid the usual pop music and smoke. The mascot holding his hand has a grin as wide as the Thames.

Novak Djokovic is the world number one. In his career he has won 600 matches and only lost 140. He has 47 titles, including seven Grand Slams. Unlike his peers Roger Federer and Rafael Nadal, however, he's rarely spoken about as a true great of the game. Why is that? Does he not get the credit he deserves? How many Grand Slams make you great? Do get involved through Twitter,, externalFacebook, external or text 81111.

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Earlier today, Stan Wawrinka posted this picture on Instagram, external of his unique fan club at the O2 - although if you look carefully at the guys on the back row, they also have 'C'mon Roger' on their tee-shirts.

What happens if the Swiss duo meet in the latter stages? Back to their famous neutrality I suppose.

Piers Newbery
BBC Sport at the O2 Arena in London

"After seven matches we could be on the verge of confirming our first semi-finalist, although it does require Wawrinka to beat the two-time defending champion and world number one, who is on a 28-match winning streak indoors. So good luck with that, Stan. For his part, Djokovic will need to wait until Friday to secure his place whatever happens tonight."

Djokovic and the "Stanimal" hardly broke sweat in their first Group A matches. The Serb thrashed Marin Cilic 6-1 6- 1 and Wawrinka swept aside Tomas Berdych by the same score. Berdych's 6-3 6-1 victory over Cilic earlier this afternoon keeps the Czech in the mix but US Open champion Cilic looks like toast. Our man at the O2 Piers Newbery has more on tonight's permutations...

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These players have met 18 times and Djokovic leads the series 15-3. But Wawrinka will take heart from his epic five-set victory over the Serb on his way to Australian Open glory in Melbourne in May.

Evening tennis fans. How are you bearing up? Because, let's be honest the ATP World Tour finals has been a bit of a snoozefest so far. We've had seven matches and not a single one of them has gone to a deciding set. Fourteen sets of tennis and only one tie-break.

The tournament is screaming out for a contest to awaken it from its slumber and we may just have one on our hands tonight. It's the world number one Novak Djokovic against Australian Open champion Stanislas Wawrinka and it's coming your way in a matter of minutes.