Bolt, who has been struggling with injury and whose only previous 100m race this year saw him clock a sluggish 10.09 seconds in a victory in the Cayman islands a month ago, was quickly out of the blocks but he could not push on as American Gatlin took the win in 9.94 secs.

Bolt crossed in 9.95 secs with Frenchman Jimmy Vicaut third in 10.02 secs.

Six-time Olympic gold medallist Bolt told BBC3: "I got the perfect start that I wanted, then about five steps in I stumbled a bit and that kinda threw my game off.

"My legs didn't feel like my legs coming into the straight. I guess I need to do more strength work.

"At least I got under 10 seconds."

A delighted Gatlin said: "It feels good. I'm not really worried about who's in the race, I just want to get a good race pattern together.

"Usain Bolt is a great competitor and a great champion, so to come out here and have a victory it just shows it's been a good season so far.

"I just want to be confident and dominant when I run, no matter what the time is.

"It's about the dog fight, it's not about running 9.6, 9.7 at this point in time, it's about putting on a great show for the fans and I think the fans tonight saw we put on a great show."

Shara Proctor produced the best performance of the British athletes taking part in Italy tonight as she earned third in the long jump.

The 24-year-old recorded a season-best distance of 6.91 metres in the final round, with reigning Olympic champion Brittney Reese of America taking the win with 6.99m.

Proctor was the only Briton to claim a podium place, with world silver medalist Hannah England taking fourth in a strong 1,500m women's field after clocking 4:03.91 - Lisa Dobriskey coming home 10th - while Nigel Levine also finished fourth in the men's 400m.

Levine (45.64) came home just ahead of team-mate Michael Bingham (45.69) with Martyn Rooney (46.31) finishing ninth. Former Olympic champion LaShawn Merritt took the win in 44.96.

In the 400m hurdles, reigning world champion Dai Greene began his season with fifth in a time of 48.81. American Johnny Dutch, who boasts the fastest time in the world this year, won in 48.31.

Former world champion Phillips Idowu, also making his Diamond League debut this year, finished seventh in the triple jump with a season's best 16.44 with Christian Taylor of the United States emerging victorious with 17.08.

Also, Eilish McColgan was 10th in the 3,000m steeplechase, although her time of 9:41.50 saw her secure the IAAF World Championship A qualifying standard, while Steve Lewis failed to record a height in the pole vault after failing three times at 5.50m.