U.S. Olympic Marathon Trials Contenders

Davila, 28, steadily improved since placing 13th at the 2008 Olympic marathon trials. She went on to finish fifth at the 2008 Chicago Marathon and, last year, second at the Boston Marathon in the fastest American time ever in the event. Davila's Boston time -- 2:22:38 -- leads the field of 223 women vying for three Olympic spots in Houston on Saturday.