Triumphant Michael Phelps did not need to rely on hi-tech swimsuit wizardry to reaffirm his worth at the world aquatics championships.

He came to Rome a little rusty after a post-Beijing Olympics break, including a three-month ban for being photographed inhaling from a pipe used to smoke marijuana, but the American still left Italy with the most medals.

His victory over big rival Milorad Cavic in Saturday's 100 metres butterfly final, where he also stole the world record back off the Serb, was the standout race of the week-long swimming competition and one of the best duels seen for years.

The defeat by Germany's Paul Biedermann in Tuesday's 200 freestyle final had threatened to derail his charge to five golds but he stormed back with extraordinary determination.

"I never back down from challenges, I love challenges," said Phelps, who also won with the US team in the 4x100, 4x200 freestyle and 4x100 medley relays.

His successes came despite his Speedo bodysuit being widely regarded as less performance-enhancing than other models, while he only wore long pants in his 200 butterfly victory.

With the usually strong Australians generally flopping, Phelps' achievements helped to slightly restore swimming's battered image following the chaos over costumes.

Governing body FINA permitted the latest all-polyurethane suits for the worlds knowing they would prompt a flood of world records, but then messily announced during the championships that they would be banned from January.

An unprecedented 43 world records fell in Rome and a return to textile costumes means they will be difficult to surpass.

Federica Pellegrini would almost certainly have won the 200 and 400 freestyle titles without the suits but the Italian's two world records in the finals were so jaw-dropping that swimming's critics had a field day.

Brazil's Cesar Cielo Filho also notched a freestyle double in the men's 50 and 100 while shock golds for Hungary's Daniel Gyurta and Serbia's Nadja Higl in the men's and women's 200 breaststroke showed romance was not dead in the water.

Rome organisers also came away smelling of roses after a successful hosting of the two-week event following serious delays in preparation.

The cleverly converted tennis courts at the Foro Italiaco were fitting venues for a nail-biting men's waterpolo final won by Serbia and more Russian superiority in synchronised swimming.

A storm which hit the open water facilities at Ostia did not prevent German Thomas Lurz from seizing gold in the 5km and 10km races while British 15-year-old Tom Daley grabbed the headlines with victory in the 10m dive to stun the dominant Chinese.