BEIJING:  US Open champion Flavia Pennetta struggled in her first match since winning her maiden Grand Slam, needing nearly 2 1/2 hours to beat Chinese wild card Han Xinyun 7-5, 4-6, 6-4 in the first round of the China Open on Sunday.

Han broke the third-seeded Pennetta early in the third set to take a 2-0 lead, but the Italian rallied to win six of the next eight games to close out the match. Pennetta had 41 winners to 35 unforced errors and broke Han's serve eight times.

Pennetta rose to a career high No. 6 in the world after defeating compatriot Roberta Vinci to win the US Open last month before announcing her retirement at the end of the season.

In other matches, Sara Errani of Italy upset second-seeded Petra Kvitova 7-5, 6-4 and Sloane Stephens of the United States defeated ninth-seeded Karolina Pliskova of the Czech Republic 6-3, 6-2.