Melbourne: Michael Phelps won a record-equalling sixth gold medal at the World Championships on Saturday to remain on course for his historic bid to win eight titles.

The 21-year-old beat his American teammate Ian Crocker in a frantic finish to win the 100 metres butterfly final in 50.77 seconds.

The only other man to win six titles at a single World Championships was Australia’s Ian Thorpe, at Fukuoka, Japan, in 2001. American Mark Spitz won seven golds at the 1972 Munich Olympics.

Phelps is an overwhelming favourite to complete his quest on Sunday’s final night of competition by winning the 400 individual medley and helping the US win the 4x100 medley relay.

Crocker had to settle for the silver in 50.82 with Albert Subirats of Venezuela grabbing the bronze in 51.82.

Libby Lenton enhanced her claims as the outstanding female swimmer of the championships by anchoring Australia to a world record in the 4x100 medley relay to collect her fourth gold medal.

Lenton teamed up with Emily Seebohm, Leisel Jones and Jessicah Schipper to win in 3:58.31, slicing 0.56 off the mark Australia set at last year’s Commonwealth Games in Melbourne.