A stomach bug may be keeping Olympic gold medallist Mo Farah out of Friday night's 10,000 metres but it's not keeping him out of the Prefontaine Classic.

Farah will run in the 5,000 metres on Saturday at the elite Diamond League event, going up against fellow Olympian Galen Rupp. While Farah is British and Rupp is American, the two are training partners and close pals.

Farah picked up the virus at the Oxy High Performance meet in Los Angeles two weeks ago. It forced him to miss a few days of training.

"Having an extra day of rest and running half the distance is probably in his best interest," Rupp said.

Farah was one of the star attractions of the Prefontaine Classic's "distance night" in advance of the main meet on Saturday. The event will still include world record holder Kenenisa Bekele of Ethiopia.

Farah thrilled the home-country crowds at the London Olympics by winning gold in both the 5,000 and 10,000 metres. A British newspaper ran a banner headline exclaiming "Golden Mo-Ment!"

He was the seventh man to win at both distances at a single Olympics, the first from Britain. He was also the first man to win the Olympic 5,000 title as the reigning world champion.

Rupp finished second to Farah in the Olympic 10,000 for the silver medal. The two athletes, who are coached by Alberto Salazar as part of the Nike Oregon Project, have been training together recently in Park City, Utah.

"We both understand that we're both pretty fierce competitors and both want to win," Rupp said Friday. "Anything that happens on the track we don't take personally. In fact, we see it as an advantage to have each other in a race. We tend to key off each other."

Farah won the 5,000 at the Pre Classic last year in 12 minutes, 56.98 seconds, the fastest time ever run in the United States. And for Rupp, the Prefontaine meet is special because it's at the University of Oregon's Hayward Field, his home track in college.

Other athletes participating in the Pre include Olympians Nick Symmonds in the 800 metres, Allyson Felix in the 100 and LaShawn Merritt in the 400. Olympic gold medallist Sanya Richards-Ross was a late entrant in the women's 400 after a foot injury held her out of the adidas Grand Prix in New York.

The women's 800 metres will include Bronxville (N.Y.) High School junior Mary Cain, who two weeks ago set a high school record in the 1,500 metres with a time of 4 minutes, 4.62 seconds. The mark gave her the "A" standard to compete at the world championships.

Kenyan David Rushida, world record holder in the 800, had to withdraw from the Pre because of a right knee injury. Rushida had an MRI on Thursday in Eugene, revealing bruising of the bone and ligaments.

This year's 10,000 was originally supposed to be the IAAF World Championship Trials for Ethiopia, but meet organizers said the Ethiopian Athletic Federation decided to go in a different direction.