World 100m record holder Usain Bolt returned to the track after a near 10-month absence with victory at the Diamond League meeting in Rome.
But it was a rather lacklustre display by the colourful Jamaican's own standards, winning in 9.91 seconds.
"I was nervous, as it was my first race of the season. I didn't think it went well and the nerves got to me," the sprinter said.
"It was a totally bad race and I'm just pleased I won."
Bolt continues his Diamond League season in Oslo in Norway on 9 June, in preparation for the World Championships in South Korea in August.
"Today was just to get the cobwebs out," he added. "But I got through the race injury free and now I'm just looking forward to the next race."
Bolt was given a rapturous reception as he was introduced to the 47,000 fans in the stadium, but when it came to the race itself, he was slow out of the blocks.
But in his first outing since losing to Tyson Gay in Stockholm on 6 August last year, the Jamaican star found his rhythm in the second 50m to edge past compatriot Asafa Powell, who ran 9.93, in the final few metres.
French European champion, Christophe Lemaitre, crossed the line third, in 10.00.
BBC Sport commentator Steve Cram said: "He was poor out of the blocks even if he did pick up towards the finish.
"He is definitely going to have to go away and work hard on that. By his very high standards you could almost call it average. I have no doubt there is more to come from him.
"But if Tyson Gay was watching, he would be pretty pleased and thinking 'Bring it on'."
Meanwhile, Britain's world and European triple-jump champion, Phillips Idowu, showed strong form as he leapt to a world-leading distance of 17.59m, some 30cm ahead of nearest rival, Christian Olsson.
Swede Olsson had led the competition with his first-round jump of 17.29m, but Idowu, 32, responded well to win the event with an impressive second-round leap.
In a highly anticipated women's 400m, American Allyson Felix stormed to victory to improve her season-best time to 49.81. World champion Sanya Richard-Ross could only manage fifth.
There was a positive British display from Perri Shakes-Drayton, who ran a personal best time of 51.47.
Felix was unable to make it a double victory in Rome, finishing fourth in the 200m, 45 minutes later, behind fellow US athlete Bianca Knight, who won in 22.64.
Dai Greene, Britain's European and Commonwealth champion, gave a powerful display in the 400m hurdles, crossing second behind LJ van Zyl in 48.24.
South African Zyl, who broke the 48-second mark for the third time this year, clocked 47.91.
In the 1500m, Lisa Dobriskey finished 10th, well behind winner Maryam Yusuf Jamal.
Favourite before the race, Ukrainian Anna Mishchenko was felled with 500m to go, and finished in fourth.
Blanka Vlasic never looked like losing in the high jump. A strong performance from the Croatian won the event with 1.95m.
100m hurdler Tiffany Ofili-Porter was no match for race-winner Dawn Harper, as she finished last in 12.91 seconds.
There was also a handful of Britons running in non-Diamond League events, also held in Rome.
Christian Malcolm and Leon Baptiste came sixth and last respectively in the 200m, with times of 20.95 and 21.16.
Martyn Rooney tested Chris Brown of the Bahamas in the 400m, but the Londoner weakened in the final 70m to stop the clock at 46.12, in second place.