Roddick sits sixth in the ATP world rankings
Defending champion Andy Roddick suffered a surprise first-round exit at the China Open following a straight sets defeat by Lukasz Kubot.
The third seed was beaten 6-2 6-4 by the 27-year-old qualifier from Poland, who is ranked 143 in the world.
"I was just trying stuff out there and nothing seemed to be working that well," said Roddick of his performance.
World number two Rafael Nadal survived a stern examination to overcome Cyprus' Marcos Baghdatis 6-4 3-6 6-4.
The Spaniard has not played a competitive match since his US Open semi-final defeat by eventual champion Juan Martin del Potro because of an abdominal strain.
"I didn't play my best tennis, but I'm very happy with how I played in the last four games, very aggressive with the forehand and going to the net," said Nadal after his 130-minute match.
"My body is okay today, and tomorrow, I hope."
Compatriot and fifth seed Fernando Verdasco fought back from a set down to beat American Robby Ginepri 6-7 6-1 6-2.
Seventh seed Fernando Gonzalez also booked his second-round spot, along with James Blake and Ivan Ljubicic.
The Croatian beat France's Paul-Henri Mathieu 7-6 4-6 6-1, while Chilean Gonzalez overcame world number 19 David Ferrer 7-5 6-4.
Blake needed three sets to beat Germany's Florian Mayer 6-3 3-6 6-3, while Marat Safin had no such problems against Argentina's Jose Acasuso, winning 6-4 6-2.