'Hamilton has just got to use his brain'

The Formula One world championship is poised for a thrilling climax with three drivers in with a chance of winning with two races to go.

Lewis Hamilton of McLaren heads into Sunday's race in China with a five-point championship lead over Ferrari's Felipe Massa, with BMW Sauber's Robert Kubica a further seven adrift.

On paper, Hamilton should be a strong favourite, and Kubica - whose car is off the pace of the Ferrari and McLaren - should have no chance.

But the Englishman's position is not as strong as it might at first appear.

And after a season of topsy-turvy results and high-profile errors, it is clear anything could happen - especially when Hamilton appears to have more enemies out on the track than he does in the title battle.

We assess the positions of each of the three contenders.