Li Na of China hits a return to Heather Watson of Britain during their women's singles match at the US Open tennis tournament in New York August 27, 2012.  [Photo/Agencies]

NEW YORK - China's Li Na began her title bid with a rain-interrupted 6-2 6-3 victory over Britain's Heather Watson at the US Open on Monday.

The ninth seed had too much power and experience for the former US Open junior champion as she advanced to the second round following a match that was interrupted by a rain delay that lasted almost two and a half hours.

"I'm feeling a lot more confident," said Li, who lost in the finals at Montreal before winning the $2.1 million tour stop in Cincinnati earlier this month. "I'm really happy I can win the first match. Last few years, I always lose in the first round.

"I see the schedule, I say, 'Okay, you have to do it for yourself.' I have to win the first match, otherwise same like last year, I pack and go back to airport to fly back home."

After winning the first set, the 30-year-old former French Open champion recovered from 3-1 down in the second to lead 5-3 when the rain took the players off the court.

The 20-year-old, world number 71 Watson lost four of five points on her serve following the delay, punching a backhand into the net on match point.

Li successfully landed 75 percent of her first seves with no double faults and enjoyed a 28-10 advantage in winners to advance in one hour, 21 minutes.

"I was 10 years older than her, so I got more experience on the court," said Li. "I mean, she plays very good, but sometimes I have to show her how good I am."

Li will face Australian Casey Dellacqua in the second round. They have played three times, the last time in 2008, and Li has won each time.

"The grand slam, every match is tough match," said Li. "I have to be ready for every second."