We're down to the last four in the World Tour Finals after yesterday saw the conclusion of the Group B matches.  Roger Federer and Juan Martin Del Potro are through from Group A and they are joined by Robin Soderling (our 20/1 outright pick) and Nikolay Davydenko - who squeezed in ahead of our other selection, Novak Djokovic, by virtue of winning one more set.  

One of the reasons for not backing the Russian in the outright betting was that he brings a 0:12 record against Roger Federer into their SF today.  The world No.1 is 8:0 on hard courts against his opponent and overall leads Davydenko by 27:4 in sets.  As such, not easy to make a case out for Davydenko winning a set, let alone winning the match.

That said, Federer certainly hasn't looked at his best this week, although his win over Murray showed he can pull out the stops if necessary, and at the end of a long year he has nothing left to prove.    

Federer (2/7) is too short to back.  Davydenko (3/1), looking at this week's form in isolation, has a chance but even that is hard to justify purely on the stats.  Better to go for a three set match (7/4) as this could be closer than the prices suggest.  Also, on the figures, Federer has won 13 of his 27 sets either 7-5 (11/1) or 7-6 (5/1) - that might be worth a small bet.
  
Soderling and Del Potro are 1:1 on past meetings.  Both tight matches with the odd break of serve here and these settling the match.  Naturally, we have to stick with our man - although the South American had a day off yesterday whilst Soderling only played last night ... these things do matter.

Just on the prices, Soderling (13/8) does seem a little big.  And with two big servers on show we must go for over 23.5 games (5/6) as even a two set match could see this mark beaten.

We're back tomorrow with more free tennis tips for the final.