Olympic double bronze medalist Walter Dix does not buy the talk that America, without Tyson Gay, will have no answer for Jamaica's Usain Bolt and Asafa Powell at next month's World Championships.

US championship victories at 100 and 200m have convinced the Floridian he can be a shock factor in the short race and medal in the longer run at the Aug 27-Sept 4 World Championships in South Korea.

"I love to prove people wrong," Dix, who will compete in Canada's National Track League meet in Toronto on Wednesday, said.

World record-holder Bolt recently said he believed without world silver medalist Gay, who underwent hip surgery last week, his biggest challengers in South Korea would be his Jamaican teammates and fellow Caribbean sprinters.

"I have always had the confidence I can beat those guys," said Dix, who won the US championships in respectable but not Bolt-like times. "I just haven't been able to stay healthy since 2007. This is the first year I am doing that."

The improved health and good results so far have sparked thoughts Bolt could be beaten in Daegu, which is one reason Dix is competing in Toronto and ran on Sunday in Halifax, Nova Scotia.

The American needs to fine-tune his start and the early portions of his 100m if he is to have a chance against Bolt at the World Championships.

"If I can just come out of the blocks next to him, if I can be with him or a step ahead at 40 meters, I think it is a wrap," Dix said of his plan to dethrone Bolt.

"I don't see myself losing to him. I ran down Asafa a couple of times (in races) and I think Bolt and I have about the same top-end speed ... I don't think he is going to pull away from me too much."

The ever-hopeful Dix may need a refresher course in events of the 2008 Olympics, where the lanky Bolt was untouchable in Beijing once he unfurled his long stride pattern, romping to world records in the 100 and 200.

Dix claimed bronze in the 100 and was elevated to bronze in the 200 after two athletes who finished ahead of him were disqualified.

Bolt dropped his world records to 9.58 seconds in the 100 and 19.19 seconds in the 200 at the 2009 World Championships. Dix has bests of 9.88 (in 2010) and 19.69 (in 2007).

Yet, Dix insisted he could run with Bolt and Powell.

"When I saw 9.5. and 9.6 (for Bolt), I believed I could run 9.7 or 9.6," he said, "and I always thought I was going to run 19.3 (in the 200)."