LONDON >> Michael Phelps ended his career with another gold and Missy Franklin completed her storybook Olympic debut with a world record as the United States swept the men’s and women’s medley relays at the London Olympics on Saturday.

Phelps leaves the sport with a record 18 golds and 22 medals overall. At these games he won four golds and two silvers.

In the final swimming event of the eight-day meet, the Americans clocked 3 minutes, 29.35 seconds.

Matt Grevers led off in the backstroke leg, Brendan Hansen swam the breaststroke, Phelps did his usual butterfly leg and Nathan Adrian was the anchor in freestyle.

The Americans trailed when Phelps dove in, but he pushed them in front.

Japan touched in 3:31.26 to take the silver medal and Australia finished in 3:31.58 to take bronze.

The American women clocked 3 minutes, 52.05 seconds, slicing 0.14 off the previous mark set by China at the 2009 world championships at the height of the high-tech bodysuit era.

Missy Franklin swam the leadoff backstroke leg, Rebecca Soni did the breaststroke, Dana Vollmer competed in butterfly and Allison Schmitt had the anchor leg in freestyle.

The 17-year-old Franklin, who starts her senior year in high school this fall, finished the meet with four golds and a bronze, while Schmitt leaves with three golds, a silver and a bronze.

Australia touched in 3:54.02 to take the silver medal and Japan finished in 3:55.73 to take bronze.