Shanghai, China (My Sportsbook) - Wimbledon runner-up Andy Roddick was forced to retire from his second-round match due to a left knee injury Tuesday at the $5.25 million Shanghai ATP Masters.

The fourth-seeded Roddick, who enjoyed a bye into the second round, was leading Swiss Stanislas Wawrinka 4-3 in the first set when he called it quits on the hardcourts at Qi Zhong Tennis Center, the former site of the ATP's Tennis Masters Cup. Roddick suffered the injury a day after criticizing the ATP for its' grueling schedule.

Roddick was leading in the opening set and looking to convert a break point when he pulled up with the injury while chasing down a Wawrinka backhand.

"It was enough to make me stop a tennis match...beyond that I don't know, that's not my profession," Roddick said of his left knee.

The struggling Roddick has lost three straight and five of his last seven matches. Since reaching the Wimbledon final, the former top-ranked American is just 9-7.

Wawrinka was joined in the third round by sixth-seeded Russian Nikolay Davydenko, 10th-seeded Chilean Fernando Gonzalez and 13th-seeded Czech Radek Stepanek. Davydenko drubbed fellow Russian Igor Kunitysn 6-4, 6-2, while Gonzalez grounded Brazilian qualifier Thomaz Bellucci 6-3, 6-4 and Stepanek stopped German Andreas Beck 7-5, 6-4.

Davydenko and Gonzalez will clash in the round 16.

Seeded first-round winners Tuesday were No. 9 Robin Soderling, No. 11 Gael Monfils and No. 15 Tommy Haas. The French Open runner-up Soderling subdued Romanian Victor Hanescu 6-3, 6-4, while Monfils mauled fellow Frenchman Paul- Henri Mathieu 6-2, 6-2 and Haas handled fellow German Benjamin Becker 7-6 (7-5), 6-4.

A first-round upset came when Czech Tomas Berdych took out 12th-seeded Croat Marin Cilic 7-6 (10-8), 3-6, 6-4. Cilic was last week's China Open runner-up to Serbian star Novak Djokovic. Berdych will battle wild card and former No. 1 star Marat Safin here on Day 4.

Former world No. 1 Lleyton Hewitt was also among Day 3's first-round victors, as the two-time major champion leveled 6-foot-9 American John Isner 6-2, 6-4. Hewitt will be opposed by Monfils on Wednesday.

Other opening-round winners were Spaniard Nicolas Almagro, Serbian Viktor Troicki, Croat Ivan Ljubicic and Austrian Jurgen Melzer.

A bevy of stars will take to the courts for second-round matches here on Wednesday, including top-seeded Rafael Nadal, a second-seeded Djokovic, U.S. Open champion Juan Martin del Potro and last week's Tokyo titlist Jo-Wilfried Tsonga. The Aussie Open champion Nadal will meet American James Blake, while last week's Beijing winner Djokovic will encounter Italian qualifier Fabio Fognini, a third-seeded del Potro will tangle with Melzer and a fifth-seeded Tsonga will face Chinese wild card Shao-Xuan Zeng.

This inaugural event closes out a three-week Asian swing on the ATP and the eventual winner will take home $616,500.