Del Potro out of Shanghai Masters betting

US Open champion Juan Martin del Potro has dropped out of the betting for the Shanghai Masters after suffering a wrist injury.

He joins the likes of Tommy Haas and Andy Roddick in pulling out of the event following comments from some senior players claiming the tennis season is too long.

Del Potro retired from his second-round match against Jurgen Melzer at 5-7 1-2 having been among the favourites for the title.

His withdrawal adds to the unpredictability of a tournament which could now be grasped by Spaniard Rafael Nadal.

Sportingbet has the world number two on odds of 1.16 to beat Tommy Robredo today and Betfair has him on odds of 3.65 for the tournament, just behind Novak Djokovic at 2.72.

Nadal himself has shown few signs of tiredness in the tournament so far, although he missed out on Wimbledon earlier this year having been forced to rest through injury.

However, he backed earlier comments by Roddick on the length of the season, saying: "It's impossible to play (from) January 1 and finish December 5."

Serb Djokovic beat Fabio Fognini to make it to the third round, where he will face Rainer Schuettler.