It's very simple - the Spurs have to figure out how to get physical and bully the Lakers. That's what Boston did in the Finals, and that's what New Orleans did last week.
Against the Hornets, the physicality took Gasol out of his game, and somehow Bynum got lost.
The Spurs aren't an overly physical team, and didn't have a deep set of bigs, so this will difficult. Still, they have to find a way to do it.
And secondly, our threes must fall. We will do a good job of defending their threes, but ours have to fall.
Last key: Parker has to be very aggressive and run Fisher ragged. That's what Chris Paul did - they missed Farmar a lot in that game, and Fisher was gassed by the end.
Prediction: If the Spurs shoot well, they win. I would say they need to hit 9+ three-pointers.