Michael Phelps conquered Rome with a fifth gold medal in the men's 4x100 metres medley relay on Sunday when the American team closed an extraordinary world championships with a 43rd world record.
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.
New polyurethane swimsuits have been partly responsible for the record amount of records at the championships but they will be banned from January after criticism about how easy it has been for times to be smashed.
The next long-course worlds in Shanghai in 2011 will struggle to match Rome with future textile-only suits not expected to give swimmers an advantage.
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 U.S.
Soni had beaten the Russian into second place in the 100 final on Tuesday.
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.
"That was pretty perfect, I am very pleased as I was amongst class opponents tonight," the twice bronze medallist in the event told reporters.
"It may sound strange but there are still a few things I think I can improve on, however, I have another world record and now I am the world champion."
The noisy crowd at the Foro Italico really took to the quick sprints and the red line showing world record pace on the giant screens made them even more exciting during the championships.
One fan was especially delighted to catch Ryan Lochte's swimcap after the jubilant American had hurled it into the stands following his victory in the 400 individual medley.
Lochte, who broke Phelps' 200 medley world record on Thursday with his compatriot not competing, 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.
Australian Stephanie Rice, another Olympic champion with a big reputation, has had a competition to forget and could only finish third behind 400 individual medley winner Katinka Hosszu of Hungary despite qualifying quickest.
