Michael Phelps went out a champion on Saturday, earning gold in the last race of his Olympic career.

Competing in the butterfly leg of the men's 100-metre medley relay, the swimmer joined Matthew Grevers, Brendan Hansen and Nathan Adrian to defend the American team's perfect Olympic record in the event. The team had a first place finish in three minutes, 29.35 seconds.

The United States was second behind Japan when Phelps jumped into the pool for the third leg of the event, but the 27-year-old put down the fastest split to get back the lead for Team USA.

Freestyle swimmer Nathan Adrian held on in the final length of the pool for the win. Japan was second in 3:31.26 while Australia was third in 3:31.58.

With the win, Phelps brought his Olympic gold-medal count up to 18 -- double that of the next Olympians on the list; Soviet gymnast Larisa Latynina, Finnish runer Paavo Nurmi, American sprinter and long jumper Carl Lewis and American swimmer Mark Spitz each earned nine.

Canada's team also competed Saturday, with Charles Francis, Scott Dickens, Joe Bartoch, and Brent Hayden, a bronze medallist in the men's 100-metre freestyle, finishing eighth.

The Olympic race was also the last for three of Canada's swimmers. Dickens, Bartoch and Hayden have all said they will retire following the close of these Games.