Murray is in a strong position at the top of the group standings after two matches and the Scot needs only a set to make the semi-finals, but, of course, there's a bit more than that riding on this match.
With 200 ranking points on offer for each round robin stage match win Murray needs to keep winning to hold Novak Djokovic at bay in the race for the year-end number one spot.
The only scenario where Murray would fail to qualify for the semis is if he loses in straight sets to Wawrinka and Kei Nishikori also defeats Marin Cilic (in two or three sets) in the night match.
And for Wawrinka the reverse is true, so the Swiss needs to beat Murray 2-0 and then hope that Nishikori takes down Cilic, in which case Wawrinka and Nishikori would qualify.
Given Stan's lack of consistency it's hard to see him beating Murray in two sets, but it's not out of the question, with three of the pair's last four clashes going the way of the Swiss and in straight sets, too.
It was 2-0 to Stan when they met here at the O2 a year ago and Murray hasn't beaten Wawrinka on a hard court at main level since Tokyo 2012, so he can't take anything for granted on Friday.
You've also got to wonder how much energy his three set-plus battle with Nishikori has taken out of what must surely have been pretty heavy legs and his starts this week in Docklands have been awful.
Overall in their career series it's been tight, with Murray leading 9-7, and there's little in the service holds in those matches, with Murray holding his serve 76.7% of the time against Wawrinka, who holds 73.4% of the time against Murray.
They've played just one tie break in their last 23 sets against each other at all levels going back to 2010 and that was here last year, so on those numbers you'd expect no breakers, but it was much the same against Nishikori and there was one in the first set there.
Obviously Wawrinka has to win the opening set and after a typically slow start to the tournament against Nishikori we saw a much-improved showing from the US Open champ in his narrow win over Cilic.
Cilic was very wasteful on Stan's second serve and you'd imagine that Murray would be much more clinical, but he seems weighed down with a combination of fatigue and the pressure of playing here at a venue he's never played his best tennis at.
I can't see any value at all in Murray's price of 1.30 in these circumstances and more so given he was a 1.80 chance at the French Open this year and here at the O2 last year against Wawrinka.
This match is mainly about set one and Stan to win it at 3.20 looks a much better value proposition than 1.30 about a Murray victory.
Back Wawrinka to win set one at 3.20