Michael Phelps looks ahead to 2012 Olympics

American swimmer Michael Phelps has admitted that he can still improve ahead of next year's Olympics in London.

The 26-year-old won seven medals, including four golds, during last week's World Championships in Shanghai but he believes he can still improve.

"There are a lot of things that are really going to help me for motivation over the next year and there are a lot of small things that I can change," said Phelps.

"We have 12 months to prepare for London, and that's what I plan on doing."

Phelps was overshadowed by his American teammate Ryan Lochte in Shanghai after Lochte beat him in the 200m freestyle and the 200m individual medley to take his tally to five gold medals for the week.

Phelps, winner of eight gold medals at the 2008 Beijing Olympics, will retire from swimming after the 2012 Games.