PHILADELPHIA — National champion David Sender is day-to-day for the Olympic trials after spraining his ankle in a fluke training accident.

Sender was on crutches when he returned to the arena Wednesday night, but the MRI showed no torn ligaments in his right ankle and he immediately began treatment in hopes of being able to compete at trials. The men's competition at the gymnastics trials begins Thursday and concludes Saturday.

If Sender can't compete, he would have to petition directly onto the team. Reigning Olympic champion Paul Hamm, who broke his hand at last month's national championships, has already submitted a petition. Two gymnasts will be selected to the team after Saturday's competition, and the rest of the team and/or a training squad will be announced within 24 hours.

Sender was working on high bar Wednesday afternoon when he took a harmless fall. The bar continued to shake afterward, and he jumped up to steady it. But when he came back down, only the top half of his right foot landed on the thick mat and his foot rolled over. Sender fell to the ground in pain, grabbing his ankle.

He was unable to put weight on the ankle as he was helped off of the podium, and he left the arena in a wheelchair with his right foot elevated.

Sender, a Stanford senior, won his first national title last month after Hamm got hurt. He leads the points standings that the selection committee will use to help put together the men's team for the Beijing Olympics.