ALBERTO Contador is poised to win the Tour de France by one of the narrowest ever margins, after clinging to the yellow jersey following the stage 19 time trial from Cognac to Angouleme.

The stage, one of the greatest time trials ever witnessed on the Tour, was won by Contador's Discovery Channel team mate Levi Leipheimer, who started the stage in third place overall and covered the 55.5 kilometres in just 1:02.44.

The American's ride brought him to within 10 seconds of the second-placed rider Cadel Evans, who finished second on the stage and himself reduced Contador's overall lead to just 23 seconds.

At one point Evans looked set to overhaul the Spaniard, but Contador dug deep in the final kilometres of the stage and should now hold the yellow jersey during Sunday's final stage to Paris.