Usain Bolt of Jamaica celebrates after winning the men's 100 metres event at the Golden Gala IAAF Diamond League at the Olympic stadium in Rome May 26, 2011. [Photo/Agencies]

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ROME - Usain Bolt summoned up just enough energy to get past Jamaican compatriot Asafa Powell at the line to win the 100 metres on Thursday at the third Diamond League meeting of the season which was dominated by Americans.

The Olympic champion and world record holder, in his first competitive outing since losing to American Tyson Gay nine months ago, started slowly but powered ahead in the last five metres to win in 9.91 seconds in humid conditions.

It was his ninth victory in 10 races against Powell, who ran 9.93 with Frenchman Christophe Lemaitre third in 10 seconds.

"I don't think I should be judged on today's performance," Bolt told reporters. "It was my first race for nine months and I was nervous. I had to get the cobwebs out and the muscles going but it's a good start to the season by winning."

Italian Andrew Howe brought the Olympic Stadium to its feet in the men's 200. Lifted by the crowd in the final straight, he powered home in 20.31 seconds ahead of Jamaican Marvin Anderson (20.49) with Trinidadian Rondel Sorrillo in third (20.68).

American Khadevis Robinson, 35, caused a major upset in the 800 metres, setting his best time of the year as he cruised to victory in 1:45.09 ahead of South African Mbulaeni Mulaudzi (1:45.50) and Kuwaiti Mohammed Khalaf Al Azemi (1:45.52).

"Nobody could have expected I'd win here," he said. "I felt good, everything went well and the oldest man in the race won."