Though Gay had just won the 200-metre race at the London Grand Prix in 20.00 seconds, he required painkillers to numb a groin injury and went straight from the track to a treatment room at Crystal Palace.

For Gay, making the worlds in Berlin is as much a mental as it is a physical challenge. The 26-year-old American remains confident of defending his 100m and 200m world titles against Bolt, the Olympic champion and world record-holder, although he is "taking it one day at a time".

"My groin has been tight on me, I'm trying to take a little Advil (pain killer) to run through the pain," Gay said. "Right now, I'm running on faith and that's more dangerous than anything. I don't feel anything when I hear the gun. I just run and I'm dangerous.

"It's after that I feel it."

clear lead

In London yesterday, Gay overtook fellow American Wallace Spearmon on the bend and held a clear lead going into the straight, allowing him to relax in the final 30 metres.

"I didn't get to warm up like I wanted to because of the (injury) situation," Gay said. "The way I slowed down it would definitely have been 19-something (seconds)."

Gay's motivation to make it to the track in Berlin is the opportunity to reassert himself in the sport. Bolt established himself as the world's fastest man with a series of astonishing performances at the Beijing Olympics last August, setting world records in the 100 and 200 while also being part of the Jamaica team that broke the world mark in the 400-metre relay.

A year earlier at the 2007 worlds in Osaka, it was Gay recording a clean sweep of those events. The Beijing plans, though, were stymied by a hamstring injury, and there's a sense of history repeating itself for Gay.

"I'm just taking it one day at a time, it's just frustrating. Anytime a sprinter feels any type of nagging injury pain they get frustrated and the mind has to get strong again," Gay said. "I haven't been training for a couple of weeks. I've been trying to keep under the radar, mentally I'm just trying to get through this groin situation I have but I should be OK."

fastest 200

Gay has run the fastest 200 in the world this year - 19.58 in New York in May. Bolt's best this season is a 19.59 this month in Lausanne, Switzerland.

"I think he (Gay) has a lot of time to get over it," Bolt said. "So he should be ready."

Clutching his left leg, Gay conceded: "Bolt is bound to be confident - right now he has the best of the 100 and I'm still working on it. He knows I'm probably one of the only ones close to either beating him or getting a record. He knows that.

"I feel I haven't proved myself until I break the world record, that's what it's all about."

Gay will now go to Stockholm for Friday's DN Galan meet. But first, that troublesome groin will be receiving some medical attention.