LONDON — American Sarah Groff surged into medal contention on the final lap of the run and led the United States with a fourth-place finish Saturday at the 2012 Olympic Games women's triathlon at Hyde Park.

Groff, of Hanover, N.H., recorded a time of exactly 2 hours on the 1,500-meter swim, 43-kilometer bike, 10-kilometer run course. She was 12 seconds off the pace of gold medalist Nicola Spirig of Switzerland and silver medalist Lisa Norden of Sweden, who both finished in 1:59:48. Spirig was declared the winner in a photo finish, while Australia's Erin Densham took bronze in 1:59:50.

“My goal going into this race was just to be there with 1,000 meters to go. I was. You know, I've got to be proud of that. Fourth is the 'worst' position to be in but, at the end of the day, I'm an Olympian. I get to showcase this awesome sport to millions of people. I'm really proud to be on this team. Obviously it would have been better to come home with a medal, but I'm proud of the process and proud of our team,” Groff said.

Laura Bennett, of Boulder, Colo., was 17th in 2:02:17, while Gwen Jorgensen, of Milwaukee, was 38th in 2:06:34 after suffering a flat tire on the bike.

The eventual medalists pulled away from Groff over the final 1,000 meters to secure their spots on the Olympic Games podium, while Groff, who notched the day's fifth-fastest run split at 33:52, took an impressive fourth in her Olympic Games debut.

“If you don't have a kick, you don't have a kick. I didn't have it. There's nothing you can do at that point,” Groff said about the finish. “I guess you hope that somebody blows up or falls or something, but at the end of the day I did what I could. I put it all out there.”