By Gene Cherry

RALEIGH, North Carolina (Reuters) - Former world champion Tyson Gay said he was unlikely to run the 200 meters at this month's U.S. trials, effectively ending his chances of facing world record holder Usain Bolt over the distance at this year's world championships in South Korea.

Although the American said he was still planning to run the 100m at the U.S. trials and hoped to face Bolt at the worlds, he said he was resigned to skipping the 200m because of fitness concerns.

"It's about 90 percent (that he will miss the 200m)," he told Reuters Wednesday.

"I have honestly missed so much training this year because of my hip and everything, it is very difficult to say when I will run a 200."

The world silver medalist, who ran the year's fastest 100m when he clocked 9.79 seconds in a preliminary race in Florida last weekend, will face Jamaican training partner Steve Mullings at the New York Grand Prix on Saturday. Mullings is the season's second-fastest sprinter, having run 9.80.

"I know how much training I have been missing," Gay said.

"Some people think I may be playing games, but I don't play games. I run with so much heart, I overcome pain."

The injuries have not kept him from training for the 100m, Gay said, "but in the 200m you have to have fitness."

Gay said he began experiencing pain in his right foot before running in Manchester in May. The pain worsened after he returned to his Florida training base and eventually spread from the middle of his foot to the heel and then to his right knee, costing him valuable training time.

Because he will miss the 200m at the U.S. trials, he will not run the event in Europe later in the season but he plans to compete in both events at next year's London Olympics.

Gay won the 100m and 200m at the 2007 world championships in Japan before Bolt completed the coveted sprint double at Berlin two years ago, breaking his own world records in both events.

(Editing by Julian Linden)