Tyson Gay, the 100metres world champion, is expected to be fit for Beijing despite picking up an injury at the weekend.

The 25-year-old strained a muscle at the US Olympic trials but is confident he will return for the lucrative Grand Prix meeting at Crystal Palace at the end of the month, when he is set to face Jamaica's Olympic champion Asafa Powell.

Gay failed to qualify for the 200m after pulling up during in his quarter-final at the trials.

The injury has been diagnosed as a light muscle strain, leading to a likely two-week lay-off.

His spokesman said: "Tyson is expected to engage in active rest for up to 12-14 days, with light physical activity increasing through that period, and then resume training."

The London meeting is set to pit two of the men who, along with Powell's Jamaican team-mate and world record holder Usain Bolt, are expected to dominate the sprint events at the Olympics. Gay, who won gold in the 100m and 200m in Japan last year, had been tipped to be Bolt's main rival in both sprint events, but the American policy of only picking the three fastest athletes in the trials means he misses out on the 200m squad.

Gay won the 100m at the trials in a wind-assisted 9.68sec. It was the fastest ever over the distance but the tailwind made the run illegal for the purposes of official records.

He also ran a legal time of 9.77sec at the trials; the fourth fastest ever and only bettered by Bolt and Powell.

"Before I went out on the track I felt a little tightness in my hamstring so I had kind of a bad feeling," Gay said.

"When I came off the first part of the curve the first two steps were fine, and then I felt it, sort of a pull, about 40 metres in.

"Once I was on the ground it didn't hurt as much as when it happened.I'll just get it worked on for a few days."

There was also disappointment for Allen Johnson at the trials. The 37-year-old 110m hurdler only cleared four hurdles before succumbing to a tendonitis injury that has plagued him all season. The 1996 Olympic champion had been hoping to qualify for a fourth Olympics.