Nadal through in Shanghai

Top seed Rafael Nadal marched into the last 16 of the Shanghai Masters with a thoroughly entertaining 6-2 6-7 6-4 victory over American James Blake yesterday.

US Open champion Juan Martin Del Potro, however, joined the growing casualty list at the tournament, retiring because of a wrist injury while 7-5 2-1 down to Austrian Jurgen Melzer.

Nadal beat Blake in three sets on his way to the semi-finals in Beijing last week and yesterday needed more than two hours to get past the man he rates as having one of the best returns in the game.

After Nadal raced away with the first set, the pair contested two absorbing sets littered with high-quality winners before Nadal, with Blake serving to take the match into a tiebreak, unleashed a sizzling forehand to clinch victory.

The Spaniard has not reached a final since the Madrid Masters in May and will continue his comeback from knee and abdominal injuries against compatriot Tommy Robredo today.

Third seed Del Potro followed Andy Roddick in departing early through injury after the American fourth seed quit with a knee problem on Tuesday.

With Roger Federer and Andy Murray skipping the tournament because of fatigue and a wrist injury respectively, Del Potro's departure is certain to intensify the debate over the length of the men's season.