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).

In the men's 400 metres, Christopher Brown of the Bahamas produced a devastating sprint in lane 7 to win in 45.16 seconds with Jamaica's Jermaine Gonzales (45.43) and Belgian Jonathan Borlee (45.53) trailing in his wake.

Results: Men: 100M: Usain Bolt (Jam) 9.91 seconds, 1; Asafa Powell (Jam) 9.93, 2; Christophe Lemaitre (Fra) 10.00, 3. 200M: Andrew Howe (Ita) 20.31 seconds, 1; Marvin Anderson (Jam) 20.49, 2; Rondell Sorrillo (T&T) 20.68, 3. 400M: Chris Brown (Bah) 45.16 seconds, 1; Jermaine Gonzales (Jam) 45.43, 2; Jonathan Borlee (Bel) 45.53, 3. 800M: Khadevis Robinson (US) 1:45.09 seconds, 1; Mbulaeni Mulaudzi (SA) 1:45.50, 2; Mohammad Al-Azemi (Kuw) 1:45.52, 3. 5000M: Imane Merga (Eth) 12:54.21 seconds, 1; Isiah Kiplangat Koech (Ken) 12:54.59, 2; Vincent Kiprop Chepkok (Ken) 12:55.29, 3. 400M hurdles: LJ Van Zyl (SA) 47.91 seconds, 1; David Greene (Bri) 48.24, 2; Angelo Taylor (US) 48.66, 3. 4 x 100M relay: Canada 38.65 seconds, 1; Italy 38.89, 2; Germany 39.09, 3. Pole vault: Renaud Lavillenie (Fra) 5.82 metres, 1; Malte Mohr (Ger) 5.72, 2; Maksym Mazuryk (Ukr) 5.62, 3. Triple jump: Phillips Idowu (Bri) 17.59 metres, 1; Christian Olsson (Swe) 17.29, 2; Alexis Copello (Cub) 17.14, 3. Shot put: Dylan Armstrong (Can) 21.60 metres, 1; Tomasz Majewski (Pol) 21.20, 2; Reese Hoffa (US) 21.13, 3.

Women: 200M: Bianca Knight (US) 22.64 seconds, 1; Kerron Stewart (Jam) 22.74, 2; Debbie Ferguson-McKenzie (Bah) 22.76, 3. 400M: Allyson Felix (US) 49.81, 1; Amantle Montsho (Bot) 50.47, 2; Francena McCorory (US) 50.70, 3. 1500M: Maryam Yusuf Jamal (Bah) 4:01.60 seconds, 1; Meskerem Assefa (Eth) 4:02.12, 2; Gelete Burka (Eth) 4:03.28, 3. 100M hurdles: Dawn Harper (US) 12.70 seconds, 1; Kellie Wells (US) 12.73, 2; Danielle Carruthers (US) 12.80, 3. 3000M steeplechase: Milcah Chemos Cheywa (Ken) 9:12.89 seconds, 1; Sofia Assefa (Eth) 9:15.04, 2; Habiba Ghribi (Tun) 9:20.33, 3. High jump: Blanka Vlasic (Cro) 1.95 metres, 1; Lavern Spencer (St Lucia) 1.92, 2; Melanie Melfort (Fra) 1.92, 3. Long jump: Brittney Reese (US) 6.94 metres, 1; Funmi Jimoh (US) 6.87, 2; Eloyse Lesueur (Fra) 6.64, 3. Discus throw: Sandra Perkovic (Cro) 65.56 metres, 1; Yarelis Barrios (Cub) 64.18, 2; Nadine Mueller (Ger) 63.17, 3. Javelin throw: Maria Abakumova (Rus) 65.40 metres, 1; Christina Obergfoell (Ger) 63.97, 2; Barbora Spotakova (Cze) 63.32, 3.