Toby Melville / Reuters

Michael Phelps smiles after racing the final leg of the men's 4x200m freestyle relay final Tuesday.

updated 4:04 p.m. ET July 31, 2012

LONDON - Swimmer Michael Phelps became the most successful Olympian ever when he helped the United States to the gold medal in the men's 4x200-meter freestyle relay at the London Games on Tuesday, winning the 19th medal of his storied career.

Phelps, who had equalled Soviet gymnast Larisa Latynina's haul of 18 medals earlier when he won silver in the men's 200 butterfly final, swum the anchor leg in the relay for the Americans.

The 27-year-old had already set the record for gold medals, winning six in Athens in 2004 and an unprecedented eight in Beijing four years ago. The relay victory was his first gold in London.

France took the silver in the relay, while China won the bronze.