US swimmer Michael Phelps adjusts his cap before a training session at the FINA World Championships in Shanghai, China, on Thursday. Wong Maye-E / Associated Press

US swimming superstar is in Shanghai with hopes of regaining the form which saw him win eight gold medals at the Beijing Olympic Games.

Michael Phelps set new standards in Olympic swimming with his eight gold medals in Beijing, and now faces the tricky task of resetting his goals in the wake of that dazzling display. Phelps has already achieved his stated aim of putting swimming - at least temporarily - at the forefront of America's crowded sports consciousness with his record-breaking run at the 2008 Games.

Once a restless kid from Baltimore who found an outlet for his energy in the water, Phelps now boasts all the trappings of modern sports celebrity - from a video game modeled on him to a tabloid photo fracas.

The triumphant pictures of Phelps with his eight Beijing gold medals draped around his neck were eventually supplanted by pictures of Phelps at play, and plenty of Internet gossip about his love life.

After a British newspaper ran a photo of Phelps nuzzling a marijuana pipe in early 2009, the outcry even had him reconsidering his plans to continue swimming through to the 2012 Olympics.

Not long after that incident he admitted he had lacked direction in the wake of his Beijing feats.

"At that time I was really lost at what I wanted to do and where I wanted to go," he said. "I needed to sort of sit down and think about if I don't swim what am I going to do? And if I swim, what do I want to do?"

Although Phelps is famous for following through once he has set his mind on something, he hasn't found it smooth sailing in the water since then.

He tried and finally rejected a new freestyle stroke designed to help him become a player in the 100m free.

His personal uncertainties in 2009 played out against the backdrop of the hi-tech swimsuits controversy that roiled the sport.

He departed the 2009 World Championships in Rome with five gold medals, including another scintillating victory over Serbian Milorad Cavic in the 100m butterfly.

Phelps became the first man to break the 50-second barrier in the 100 fly, but he surrendered the 200m free world title and world record to Germany's Paul Biedermann, who wore one of the polyurethane supersuits that are now banned.

With no major global competition on the calendar, Phelps coasted through 2010, and has arrived in Shanghai for the World Championships with a string of unexpected defeats behind him.

"After having messed around for two years it's hard to know where I stand," Phelps said as he prepared for the start of racing in the competition pool on Sunday.

"I'm taking steps in the right direction and I know that, and I think that's something that I'm fairly happy with."

Certainly Phelps has overcome adversity and negative publicity before.

After winning six gold medals and two bronze at the 2004 Athens Olympics he weathered controversy over an underage drink-driving charge. And he soldiered on after a broken wrist disrupted his preparations for Beijing.

Coach Bob Bowman, who has guided Phelps since he was 11, has long known that Phelps' determination and will are valuable competitive assets.

Now that Phelps is 26, Bowman could do little but stand back as the swimmer sorted out his post-Beijing priorities, but the coach has little doubt Phelps can add to his Olympic legacy in London.

While it's true Phelps has nothing left to prove in the Olympic arena, that doesn't mean there's nothing more to accomplish.

Phelps says he won't try to match his Beijing gold rush in London.

But even a smaller haul would add luster to his Games career, showcasing the kind of versatility and longevity for which Finnish runner Paavo Nurmi - who won nine golds at three distances over three Olympics - is still revered by Olympic historians.

"I'm excited," Phelps said. "This is going to be the start for next year. That's something I'm ready for."