Britain's Mo Farah says he is targeting the 10,000m at the London Olympics and will wait to see how he feels before deciding whether to go for a double in the 5,000m.
"I am going to run the 10,000 for sure because it is the first race," said 5,000m world champion Farah after winning the 5,000 at the Diamond League's Prefontaine Classic in Oregon.
"I will see how I feel after that. It depends how I come off in the 10,000. I would like to be fresh and not have any niggles."
Farah's time of 12 minutes 56.98 seconds in the US was the fastest in the world this year and easily beat the defending Olympic champion, Ethiopia's Kenenisa Bekele, who finished in fourth place.
Kenya's Isaiah Koech came second with American Galen Rupp in third.
Farah's time was the second fastest he has ever run over 5,000m and broke the Eugene meeting record.
"The crowd got behind me. I was really pleased. It was awesome," said the 29-year-old Farah.
"It was kind of an up and down pace. I started reasonably good then slowed down in the middle and then towards the end I picked it up again.
"The conditions were a little windy today so I wasn't as perfect as what I wanted. But at the end of the day, I think the most important thing was to get a win under my belt."
Despite having won silver in the 10,000m as well as 5,000m gold at the World Championships in Daegu, South Korea, last year, Farah insisted he would not save anything for the 5,000m which comes seven days later in the Olympic schedule this summer.
"I'll definitely put my eggs in one basket," he said. "You can't be thinking that you want a double."
Bekele, who is recently back from a calf problem, produced a season's best of 13:01.48 but it was not enough to seriously threaten the Briton.
Earlier, America's 2004 Athens gold medallist Justin Gatlin won the 100m in 9.90 seconds - despite a sluggish start - and remains unbeaten this season.
In the 110m hurdles, Britain's world bronze medallist Andy Turner came last, despite the fact that his time of 13.46 seconds was inside the Olympic A standard.
There was disappointment for Holly Bleasdale in the pole vault as she could only manage to clear 4.28m to finish seventh.
Barbara Parker ran a new British record of 9:24.24 to finish fourth in the 3,000m steeplechase, bettering Helen Clitheroe's four-year-old mark of 9:29.14, set at the 2008 Beijing Olympics.
Anguilla-born Briton Shara Proctor won the long jump with a leap of 6.84m, a new outdoor personal best. Proctor, the world indoor bronze medallist, moved up to fifth in the world rankings this season.
Phillips Idowu had less joy in the triple jump after he withdrew from the competition following three jumps. The world silver medallist pulled out after fouling his third attempt and had to settle for third with a best of 17.05m.