EUGENE – Allyson Felix blocked out the knifing agony in her right ankle and made her first run at Olympic Trials look like a jog Friday night.

Sanya Richards-Ross felt a different kind of pain.

On a night Felix cruised on auto-pilot in the 400-meter qualifying round to keep her chance at a 200-400 double alive, Richards-Ross bid a tearful adieu to the fans, after pulling up 250 meters into her lap around the track – her hamstring too tight to carry on.

“I’ve had an amazing career,” Richards-Ross said. “To have my last race be here, at Hayward Field, in front of these fans, it’s incredible.”

In addition to her four Olympic gold medals, including the individual title at the London Games, Richards-Ross holds the stadium record in Eugene – better known as Track Town USA. It was here, five weeks ago at the Prefontaine Classic, that fans got their first true glimpse of what might be coming. Richards-Ross finished seventh that day.

In this one, her first 15 steps out of the blocks were smooth, but she went from a sprint to a trot. By the time she hit the first curve on the backstretch, she was slowing. And then she pulled up completely.

“Let’s be honest, I hurt my hamstring real bad,” she said. “I worked with a great doctor just to get out on the track today.”

After she pulled up, she walked to the finish line. Fans rose from their seats and Richards-Ross blew kisses.

She earned as many of those fans through her failures as her successes – her long battle with illness and injuries, her third-place finish in Beijing that left her weeping underneath the stands, then, finally, the gold medal in London.

“Most fans have seen my heart through my running,” Richards-Ross said. “I don’t win every time I step on the track. I don’t deserve the ovation because I’m always a champion. But I think they see my heart, my determination, my desire to be a good person.”

Now, though, they’ll be watching Felix and others finish up the 400.

Felix finished second in her heat, posting a time of 51.96 seconds, then headed consecutive to the trainer’s room for treatment.

She hurt the ankle in the spring and has had a rough time coming back – forced to do most of her running the wrong way around the track so as not to put the injured ankle at more risk.

She has less than 18 hours to recover. Her semifinal heat is set for Saturday afternoon.