New York  - Canadian Aleksandra Wozniak handed two-time Grand Slam winner Amelie Mauresmo her earliest career defeat at the US Open Wednesday with a 6-4, 6-0 thrashing of the veteran Frenchwoman.

But Gallic hopes lifted on the day at Flushing Meadows as 13th seed Gael Monfils defeated countryman Jeremy Chardy 6-1, 6-4, 6-3 to open with a victory into the second round.

Wozniak, ranked 39th, was untouchable against an off-form Mauresmo, holder of 25 titles including the 2006 Australian Open and Wimbledon trophys.

But 31 unforced errors were fatal for Mauresmo, who lost in just over an hour. "It was exciting to play on the show court," said Wozniak. "I did well not to get distracted by the crowd or anything. I think I did a pretty good job with everything today".

Wozniak will next play Italian tenth seed Flavia Pennetta, who crushed India's Sania Mirza 6-0, 6-0. Li Na of China silenced screaming Portuguese teenager Michelle Larcher de Brito 6-1, 6-3.

Monfils said he's recovered well from knee and wrist injuries which bothered him in recent months - though he is still not at 100 per cent.

"I was feeling the ball well, I had a good match today. I tried to play inside the court and tried to be more aggressive. This was good."

Rafael Nadal was opening later in the first round against good friend Richard Gasquet of France, playing his first match since being exonerated of doping charges.  dpa