LONDON - Sun Yang became the first Chinese male swimmer to win an Olympic gold medal on Saturday as China swept four golds on the first full day of competition at the London Games.

The 20-year-old powered to the men's 400m freestyle victory in three minutes 40.14 seconds, dethroning South Korean Park Tae-Hwan, who only made it to the final after winning an appeal against a false start call in the morning's heats.

After overtaking Park at the final turn and touching home first, Sun climbed onto the lane rope and punched his fist in the air.

"The feeling is wonderful," he said. "It's a big dream come true."

Sun's time was just 0.07 seconds off the world record held by German Paul Biedermann.

But the most brilliant swim at the Aquatics Center was from Chinese teenager Ye Shiwen, who produced a stunning final leg to win the 400m individual medley in four minutes 28.43 seconds, eclipsing Stephanie Rice's record by more than one second.

American Elizabeth Beisle was second in 4:31.27, while Ye's teammate Li Xuanxu came third in 4:32.91.

"I thought I had lost the race after the first two legs," said the 16-year-old Ye. "But on the breaststroke I realized I was in the top 2 or 3 and I was confident I could win on the last leg."

"I dreamed of the gold medal, but never expected to break the world record. It's overwhelming," she added.

Early in the morning, shooter Yi Siling started China's gold rush with victory in the women's 10m air rifle at the Royal Artillery Barracks, the first medal event of the London Olympics.

The 23-year-old Yi, ranked No. 1 in the world, beat Poland's Sylwia Bogacka into second by just 0.7 points.

Yu Dan of China took bronze.

Yi and Bogacka advanced to the final with near-perfect scores of 399 out of 400, and Bogacka was leading until the eighth round of the 10-shot final but a wayward effort handed Yi the first place. Yi had an overall score of 502.9.

"It's very exciting," said Yi. "I have been up since five this morning. There was a lot of pressure on me. I'm very grateful to China and to my mother and father, who I love very much."

Wang Mingjuan earned China a second gold at these Games when she won the women's 48kg weightlifting division.

However, China's best hope in tennis, Li Na, suffered a shock early exit from the Olympics. The 2011 French Open winner lost to close friend Daniela Hantuchova from Slovakia 2-6, 6-3, 3-6 in their women's singles match at the All-England Lawn Club.

"I'm sad I lost in the first round," said Li. "I know we were professional players, but the Olympics are different because they only come every four years."

In one of the most anticipated clashes at the Games, Ryan Lochte prevailed over arch rival and fellow American Michael Phelps in the men's 400m individual medley.

Lochte dominated to win in 4 minutes 05.18 seconds, ahead of Brazilian Thiago Pereira and Japanese Kosuke Hagino, while Phelps finished in a disappointing fourth, failing to make the podium in an Olympic final since 2000.

"For four years I've been training hard. This is just my first event so I'm really happy. I'm ready to rock this Olympics," said Lotche.

Australia captured gold in the women's 4x100 freestyle relay with an Olympic record of 3:33.15.

Meanwhile, Britain's hopes for a good start were dealt a heavy blow as Kazakhstan's Alexandre Vinokourov upset a star-studded British team that included Tour de France winner Bradley Wiggins and Mark Cavendish to win ?the men's cycling road race.

Saturday also witnessed the first positive doping cheat at the Games after Albanian weightlifter Hysen Pulaku was kicked out for taking the banned substance stanozolol.