INDIANAPOLIS: 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 a total of 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 that start on Tuesday.

Phelps's 2009 campaign marks a departure for the man who has established himself as the world's supreme all-round swimmer.

Phelps's narrower focus will see him swim just four events here, including the less familiar 100m freestyle.

He showed his potential in the event when he clocked an American record of 47.51sec in leading off a triumphant US 4x100m free relay in Beijing. But it remains to be seen if he'll be able to challenge the likes of France's Alain Bernard and Frederic Bousquet and Australian Eamon Sullivan on the world stage.

"It doesn't matter if I'm the favorite or not," Phelps said Monday. "One thing I enjoy the most is being able to step up against anybody, whether they're faster than me or not.

"The 100 free, I know I'm not the best, but if I have the opportunity to step up and race the best, that's something I've always enjoyed."

Phelps will tackle the 100m free on Friday with Garrett Weber-Gale, Cullen Jones and Nathan Adrian among the other contenders for the top two places needed to book a world championships berth.

Phelps will kick off his campaign on Wednesday, the second day of the trials, with the 200m freestyle and 200m butterfly.

Phelps won both in world record times in Beijing, but his memory of the 200 fly, in which he was hindered by a problem with his goggles, still stings.

"I think clearly the 200 fly is a race I'm not satisfied with," he said. "That's one thing I'd like to improve on over the next few years."

Phelps is also homing in on the 100m butterfly world record, currently held by compatriot Ian Crocker at 50.40sec.

Phelps won Olympic gold in the event in Beijing, but he wasn't able to regain the world record he held briefly in 2003.

That world mark could be in the offing, however, after Phelps sliced a tenth of a second off his personal best time to win the title at the Canada Cup in Montreal on June 20 in 50.48sec.

"The 100 fly, I took a step in Montreal toward the time and the direction where I want to end up," he said. "That was a very good time, a very good swim for that part of the year."

Phelps's post-Olympic season got off to a slower than expected start after a photo of him holding a marijuana pipe surfaced in a London tabloid.

USA Swimming slapped him with a three-month ban, and Phelps himself admitted the storm of negative publicity had him questioning whether he really wanted to keep swimming.

"When I was thinking about it, I had to decide I was going to swim for me," he said. "I had to make sure I had the passion to want to do it. Once I found that passion, that's all I needed."

Phelps has lost four of his 10 races since returning in May as he grapples with a new training regime and changes to his freestyle stroke to make him more of a threat in the 100.

"I always thought that the shorter events would be easier to train for, but it's actually harder," he said. "You're swimming all race-pace pretty much every day, and your stroke has to be perfect."

Even so, Phelps said his year had been more relaxed than 2008, even allowing him to squeeze in some time on the golf course.

His rivals shouldn't expect a more laid-back Phelps at the pool, however.

"My favorite thing is to race. My favorite thing is to compete," Phelps said. "I still don't like to lose."