USA's Donavan Brazier poses after his record-breaking 800m victory at the World Championships. AFP Photo

DOHA — Donavan Brazier shrugged off the doping controversy surrounding his Nike Oregon Project training base on Tuesday to blast to 800m gold at the World Championships.

The 22-year-old American produced a tactical masterclass at Doha's Khalifa Stadium to surge away from the field in a championship record time of 1min 42.34sec, breaking the previous mark which had stood for 32 years.

Brazier is one of several World Championships athletes based at the Nike-backed Oregon Project, whose leader Alberto Salazar was hit with a four-year ban for doping violations after a four-year investigation by the United States Anti-Doping Agency (USADA).

Brazier revealed after his win he had been unaware of the investigation against the controversial running guru when he joined the training group last year.

"I didn't know anything about it," Brazier said. "I just woke up to a text this morning and found out."

Brazier emphasised that he had little contact with Salazar at the Oregon Project, where he is coached by Pete Julian.

"From the start I was only in contact with Pete Julian," Brazier said. "I was never coached by Alberto, and I never asked to be coached by Alberto.

"When the investigation started I didn't even know what the Oregon Project was. I was in junior high school when it started."

Brazier also rejected suggestions that his victory may somehow be tarnished through his ties to the Oregon Project.

"I think it would be really ignorant to associate me with that," he said.

"To even think that would be pretty ignorant.

"I'm just very sad. I've had communication with Alberto, never trained by him, but he is a good guy, and seeing him getting kind of bad reputation, it hurt him a lot."

Another Oregon Project runner, Brazier's compatriot Clayton Murphy, also raced in the 800m final, finishing eighth.

"There's a lot kind of going on today," Murphy said. 

"I just kind of try to pocket all that and really focus on on the job at hand."

Brazier had earlier ran a flawless race, settling into his rhythm on the first lap and then kicking for home down the back stretch on the final lap.

The burst of power was too much for his rivals, with Amel Tuka of Bosnia taking silver in 1:43.47 and Kenya's Ferguson Rotich bronze in 1:43.82.

"I don't know what I would have done technically better," said Brazier.

"To get the win means the world to me. I just put my trust in Pete Julian. To see it pay off means a lot to me." AFP