Andy Roddick holds his knee after ending his match against Stanislas Wawrinka at the ATP Masters tennis tournament in Shanghai on October 13, 2009. (Frederic J. Brown/AFP/Getty Images)
The 27-year-old fourth seed, who launched a scathing attack on the gruelling tour schedule on Monday, was 4-3 up and looking to convert a break point when he pulled up short chasing a Wawrinka backhand.
The American, who retired with a injured shoulder in his only previous tour clash with the Swiss, also lost the first match of his title defence in Beijing last week.
On Monday, he called for the ATP to allow the top players a break in the season or risk curtailing the careers of top players like Roger Federer and Andy Murray.
Former world number one Lleyton Hewitt cut big-serving American John Isner down to size with a 6-2 6-4 victory in the first round of the $3.24 million event.
Foot Shorter
Back at number 23 in the world after sliding outside the top 100 following hip surgery, Hewitt is nearly a foot shorter than the 6ft 9in (206cm) Isner but came up with some fine returns to disarm the Floridian."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 the 28-year-old Australian.
Hewitt will play Gael Monfils after the 11th seed took the honours in one of several matches between compatriots on Tuesday, crushing fellow Frenchman Paul-Henri Mathieu 6-2 6-2 in 54 minutes.
Sixth seed Nikolay Davydenko was the first man to reach the third round when he comfortably beat fellow Russian Igor Kunitsyn 6-4 6-2.
Davydenko reached the final of the last version of the Masters Cup tour championship here last year and is in the running for one of the three spots still up for grabs at the new season finale in London.
Chile's Fernando Gonzalez, currently in the eighth and final spot in the race to the World Tour Finals, will play Davydenko in the last 16 after beating Brazilian qualifier Thomaz Bellucci 6-3 6-4.
Swede Robin Soderling is another in the hunt for a place in London and the ninth seed helped his cause with a 6-3 6-4 first-round win over Romanian Victor Hanescu.
