(Reuters) - Meb Keflezighi and Shalane Flanagan won the men's and women's races at U.S. marathon trials for the London Olympics Saturday.

Eritrea-born Keflezighi, the 2004 Olympic silver medalist overhauled pre-race favorite Ryan Hall in the final four miles to run a personal best two hours, nine minutes and eight seconds on a crisp morning in Houston, Texas.

"To be on my third Olympic team is all I have dreamed about," the 36-year-old Keflezighi told reporters.

Hall, who led much of the race, finished second in 2:09:30.

Three-time 10,000 metres Olympian Abdi Abdirahman grabbed the final U.S. spot in 2:09:47.

Flanagan, the 2008 Beijing Games 10,000 metres bronze medalist, ran a lifetime best 2:25:38 and a trials record, to win the women's race.

Boston Marathon runner-up Desi Davila took second in 2:25:55 and Olympian Kara Goucher was third in 2:26:06.

(Reporting By Gene Cherry in Salvo North Carolina; Editing by Alison Wildey)