Swimming: Phelps vows more medals

With his eight-gold haul at the Beijing Games in the books - and an embarrassing tabloid moment behind him - Michael Phelps brings a new focus to USA Swimming's world championship trials.

"I have unfinished business," said the 24-year-old, who owns 14 Olympic gold medals and is aiming to add to that total in London in 2012.

First, however, comes his bid to make a fifth world championship team at the US trials in Indianapolis starting today.