Gay and Wariner live up to their billing

British weather again put paid to the world record hopes of Tyson Gay but the American sprinter nevertheless produced an impressive display to win the 100 metres in 10.02 seconds at the London Grand Prix on Friday night.

Gay, who clocked 10.13 in almost winter conditions in Sheffield last month, had to contend with a headwind of almost a metre as he sought to beat Jamaican Asafa Powell's mark of 9.77.

The American, who nudged a hundredth under that with the wind at his back two months ago, was out of the blocks first, picked up smoothly and finished well clear of Portugal's Francis Obikwelu (10.18) and Briton Marlon Devonish (10.26) to remain on course for a showdown with Powell in the Osaka world championships later this month.

"I'm undefeated, he's undefeated, one of us has to lose," Gay told reporters.

"That was my last race (before Osaka) I'm 100 per cent and I'm ready."

The meeting's other main draw, world and Olympic champion Jeremy Wariner, put young pretender LaShawn Merritt in his place in an excellent 400 metres.

Merritt has been pushing his fellow American all season and ran strongly to lead off the final bend.

Wariner, however, continued with his smooth, fluid stride while the big 21-year-old a lane inside him tightened up over the final 30 metres.

Wariner, who owed British athletics fans a performance after standing up following a stumbled start in Sheffield, won in 44.05 with Merritt clocking 44.23. Johan Wissman was third in 45.03, a Swedish national record.

"It was my first 400 metres race since early May and I am about where I need to be, almost but not quite," Wariner said.

Sanya Richards was also impressive over one lap, comfortably winning the women's edition in 49.80 even though she failed to make the US world championship team for the distance and will race only in the 200.

Carolina Kluft stuttered in her preparations for the defence of her world heptathlon title with a sluggish show in the 200 metres where she finished last in 24.03.

The race was won impressively by Olympic champion Veronica Campbell in 22.56 while in the men's version Usain Bolt made it a Jamaican double when he held off a strong finish from Wallace Spearmon to win in 20.06.

Bernard Lagat, now representing the United States, produced a devastating last 100 metres to overhaul Kenyan Nicholas Kemboi and win the 1,500 metres in 3:35.71.

The men's shot produced a dramatic finale as Reese Hoffa of the US won it with the final throw - which at 22.43 metres was a personal best by almost half a metre and the longest in the world this year.

That came after fellow American Christian Cantwell had gone into the lead with the penultimate throw - 21.66.