A flying visit to the Winter Olympics has provided Michael Phelps with fresh inspiration to stay ahead of his younger rivals in the build-up to the 2012 Summer Games in London.

The American swimmer said his whistle-stop promotional tour to Canada, which included watching the U.S. men's ice hockey team defeat Norway on Thursday, had whetted his appetite to add to his golden stockpile in London.

Being able to be a spectator here is even cooler, seeing what these guys are doing, he told a select group of invited reporters after arriving in the city's central business district to the sort of reception normally reserved for pop stars.

We're halfway home between (Beijing) and London so we're in the home stretch, said Phelps, looking clean shaven and wearing a dark suit and tie.

Phelps is already the most prolific gold medalist of all time after winning six gold medals at Athens in 2004 then another eight in Beijing in 2008, but has lost none of his killer instincts.

He was a bitter opponent of the use of high-tech swimsuits at last year's world championships in Rome, refusing to wear the controversial outfits even though most of his rivals did.

He lost his world record in the 200 meters freestyle to Germany's Paul Biedermann then survived a torrid battle with Serbia's Milorad Cavic before winning the 100 butterfly.

MILLION DOLLAR QUESTION

The sport's world governing body FINA has since banned the suits and Phelps believes that could give him an edge in the lead-up to London, which he confirmed will be his fourth and final Olympics.

I told myself I will not swim over the age of 30, and I will not swim over the age of 30, said Phelps, who will be 27 when the London Games take place.

Swimming is going to be swimming again, it's not going to be who is wearing what suit.

Being able to race some of the guys when we're all wearing the same suits will be interesting.

You're really going to be able to see who wants to work and who wants to make sure who stays on top.

Phelps returned to heavy training in December and has already competed at two low-key meets after adding more weightlifting, boxing and running to his training program in the pool.

He plans to use this year's Pan Pacific championships in California and the 2011 world championships in Shanghai to experiment with different combinations of events but was keeping everyone guessing about the million dollar question of exactly how many and which races he will swim in the English capital.

I don't even know, he said.

But I will say it's not eight, I'll give you that one.

Breaststroke is out of the question, the mile (1500m) is safe, the 400m free is safe, the 800m free is safe, the 400IM maybe, but probably not.

The 200IM is coming back, there will be a couple of other events. I may cancel some events though.

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