However, on a night when the final 16 of this season’s 32 Diamond Races were decided, it was far from a perfect race from the American and he was also under pressure for the entire 100m from Jamaica’s Nesta Carter, who finished with a personal best of 9.85.

Despite conditions that were hardly conducive to fast times, with only a 0.1 metre per ssecond wind on the sprinters’ backs, Jamaica’s Yohan Blake also defied the elements and went under 10 seconds with 9.91 for third place.

In addition to winning in Brussels, Gay also won the Diamond Race Trophy with 16 points after injuries brought season to a premature end for the Jamaican duo of Usain Bolt and Asafa Powell who, like Gay, are Samsung Diamond League Ambassadors.

Five days after setting the world 800m record of 1min 41.09sec in Berlin, Kenya’s David Rudisha indicated that he is more than just a time triallist by inflicting his second defeat of the season on the double world indoor champion, Abubaker Kaki.

Rudisha, who beat Kaki in an epic race over two laps in the Oslo Diamond League meeting, managed to hold off his Sudanese rival once again as he finished in 1:43.50, stretching his long legs to gain a winning margin in the home straight, with Kaki clocking 1.43.84.

Rudisha easily won the Diamond Race Trophy - and its accompanying prize money of $40,000 - with 20 points, and he remains unbeaten after 14 races - including the heats and semi-finals of both the Kenyan national championships and African Championships - this summer.

Former world 800 metres champion Janeth Jepkosgei saw off the challenge of the current world champion, Caster Semenya, and also inflicted a first defeat of the season upon Russia’s Mariya Savinova to emerge as this season’s world number one after a race in which six women had a chance of earning that distinction.

The Kenyan attacked decisively in the final 50m and won in 1:58.82, pulling clear of Savinova, who clocekd 1.59.49, and Semenya, who had won in Berlin five days earlier in what was her first big comeback race of the season, finishing strongly to take third place in a season’s best of 1.59.65.

Croatia’s Blanka Vlasic, whose performances had already made her unchallengeable in the Diamond Race for the high jump title, became the only athlete to complete a clean sweep of seven Diamond League wins this year as she earned victory with a best leap of 2.00 metres.