The one who defeated Roger Federer en route to this final should take the title.
Oh, wait. They both did that.
Okay. So. The one who returns serve most aggressively should take the title. Nikolay Davydenko, who returns to his second year-end final in a row, is capable of serving into the corners when you least expect him. But Juan Martín del Potro won't be as frustrated by the Russian's delivery as he was by the Swede's so he should find himself with more looks to break through. But Kolya returns serve about as well as anyone, leads their head-to-head 2-1 with both victories on indoor hard courts, and gave the reigning US Open champion quite a shellacking at this event last year. Still, the Tower of Tandil is a different player now than he was a year ago.
I've no doubt both of them can hoist the tour's final 2009 trophy, so I'll take another third-set breaker, a tub of popcorn, and may the most composed man win.