Paris, Jul 8 (IANS/CMC): American Tyson Gay has declared the 100 metres at the London Olympics an open affair after winning the event at the Paris Diamond League.

The former World champion was away from the blocks slowly but accelerated in mid-race to overhaul compatriot Justin Gatlin in the final metres and cross the line first in 9.99 seconds Friday.

"There are a lot of people now in the 100m, it is open for the Games," said Gay.

"(Usain) Bolt, (Yohan) Blake, (Justin) Gatlin, my training partner (Keston) Bledman. It will be spectacular."

His comments come on the heels of a double defeat for reigning Olympic champion Bolt, at the Jamaica Olympic trials last weekend in Kingston.

Blake won the event in a world-leading 9.75 seconds before returning to also win the 200 metres in another world-leading 19.80.

The defeats for Bolt have heightened speculation over a changing of the guard at the London Olympics which begin July 27.

Friday, Gay struggled over the first part of the race as Gatlin stormed to the early lead in race six. Over the last 40 metres, Gay hit back out of lane five to edge Gatlin on the line.

"I tried to be patient. I'm strong mentally and ready for challenges. Trials was a faster race but here a better one for me technically," Gay said.

"I feel pretty good considering I came back and made the team. I was under a lot of stress, mentally and physically, early in the season, but I feel a lot better now."

Jamaican Nickel Ashmeade was fourth in 10.14 seconds with countryman Michael Frater fifth in 10.14.

Trinidadian Richard Thompson, who took silver at the Beijing Olympics four years ago, was one from last in the nine-man field in a time of 10.20 seconds.

In the women's 400 metres, Novlene Williams-Mills of Jamaica clinched second in a time of 49.95 as Botswana's Amantle Montsho came home first in 49.77.

Another Jamaican, Rosemarie Whyte, finished fifth in 49.03 seconds.

Meanwhile, Puerto Rico's Javier Culston clocked a world-leading 47.78 seconds to win the men's 400m hurdles, with Trinidadian Jehue Gordon fifth in 49.03.