Meng and Yang finished in 1 minute and 41.025 seconds, fighting off the fast Sergey Ulegin and Alexander Kostoglod of Russia who took silver in 1:41.282. Christian Gille and Thomasz Wylenzek of Germany took bronze in 1:41.964.

The duo won the C2 500m race in a photo finish in Athens to give China its first Olympic gold medal in the sport.

The two made a slow start, but quickly led with powerful and fast strokes. They kept the lead till the finish line to the crazy roar of the home crowds.

The two fell into the water across the finish line after paddling to their exhaustion. The 25-year-old Yang hopped up and down and waved hands to the jubilant home fans after a life boat brought him on to the dock.

Meng and Yang were the first crew that successfully defended the title in the event at the Olympic Games.

"The gold medal means a lot to us," said Meng excitedly. "It's the first time the same crew won two consecutive Olympic gold medals in the event. We have rewritten the history of this event."

Meng took one year off after the National Games in 2005 and returned for the Beijing Games in October 2006, only to find he had to train harder to lose weight. He was over 100 kilograms then, compared with less than 90kg in 2004.

"It's not easy, especially after I got married. I had to lose weight, do a large amount of exercise and we put a lot of effort into our training," the 31-year-old said.

"My wife and son come here to watch my race and I want to dedicate this gold medal to my son."

His wife brought their 15-month-old son to join Meng in celebration and they posed for pictures on the podium to the delight of home fans.

"I almost felt out of oxygen during the last 100m but what was in my mind was the gold medal," Yang told reporters.

Coach Marek Ploch said the defending champions were under huge pressure when paddling on the home water.

"As the dark horse, there was no pressure for them in Athens," said Ploch. "But it is different here. Everybody expected them to win and they were under huge pressure."

"During the practice two weeks ago, Meng had problems with his back. He was slow and I didn't then even know if he could contest today," the Polish Canadian said in the Shunyi Rowing-Canoeing Park.

"They paddled with their hearts, not muscles. If there was another 100 to 200 meters, they could have not finished the race."

Meng did not pair with Yang until early this year, but they became favorites for the Beijing Games after winning two World Cup races in June. Chinese sports officials believed that the duo had a better chance of winning an Olympic gold when working together rather than contest in the singles.

"I returned because I could not resist the temptation of the Beijing Games, as one could have only one chance in his lifetime to compete in the Olympics on home water," Meng said earlier.

"If I missed the Games, I could regret it all through my life," he said. "I wanted to strive for a second Olympic gold and leave no regret for my sports career."