Dismayed Roddick picks up injury in Shanghai

FORMER US Open champion Andy Roddick was forced to limp out his second-round match of the Shanghai Masters against Switzerland's Stanislas Wawrinka on Tuesday.

 CROCKED: Andy Roddick, having complained about the length of the ATP Tour, gets injured in Shanghai

Roddick, seeded fourth, was leading 4-3 in the first set until he suffered an injury to his knee, just a day after hitting out at the length of the ATP Tour season.

The American has been calling for a break during the season to avoid risking bringing a premature end to the careers of the top players on the circuit.

Neither world number one Roger Federer and Britain's Andy Murray are present in China, both recovering from fatigue and a wrist injury respectively.

And Roddick could not hide his frustration at having to bring his competition to a premature close, with his place at the World Tour finals at the O2 Arena next month still not secure.

"Trust me, as frustrated as the Chinese fans are that we're not here, I promise you we're more frustrated," added Roddick.

"It was enough to make me stop a match - beyond that I don't know. My concern now is to find out what we are dealing with."

Meanwhile, former world number one Lleyton Hewitt eased his way past big-serving American John Isner 6-2, 6-4 to book a clash with France's Gael Monfils, who overcame compatriot Paul-Henri Mathieu.

"It's a matter of just taking your chances when you get into it against those guys, and I did that exceptionally well today," said Hewitt.

Elsewhere, Chile's Fernando Gonzalez, currently in the eighth and in the final spot in the race to the World Tour Finals, will play Russia's Nikolay Davydenko in the last 16 after beating Brazilian qualifier Thomaz Bellucci 6-3 6-4.