Phelps picks up fifth Rome gold

Phelps, who arrived underprepared after taking six months off following his record eight golds at last year's Beijing Olympics, ended up with the biggest collection of wins over the week's competition to confirm his supremacy of men's swimming.

"I think it's not how you start, it is how you finish," the 24-year-old told reporters having lost the 200 freestyle on Tuesday before adding 100 and 200 butterfly golds to two freestyle relay victories.

The United States blasted through the open air pool in three minutes 27.28 to obliterate their previous world record of 3:29.34 set when winning gold in Beijing.

Germany's Britta Steffen broke one of the four world records of Sunday's closing session to seal the women's 50 freestyle gold having credited her suit for Friday's victory in the 100 with another record.

Russia's Yuliya Efimova surged to a world record of 30.09 in the 50 breaststroke final to turn the tables on Rebecca Soni of the US.

Britain's Liam Tancock earlier carried on where he left off in Saturday's semis by shattering the world record again to steal the glory in the men's 50 backstroke. American Ryan Lochte hurtled to the 400 individual medley. Lochte led an American one-two with Scott Tyler Clary beating third-placed Hungarian Laszlo Cseh.

Tunisia's sporting hero Oussama Mellouli was too tired for a big celebration after adding world championship gold to his Olympic 1,500 freestyle title after outlasting Canada's Ryan Cochrane in the epic race.