World 200m and 400m record holder Michael Johnson yesterday dismissed claims from Justin Gatlin's coach Trevor Graham that the sprinter's failed drugs test was a case of deliberate sabotage.
Gatlin, the world and Olympic 100m champion and current joint 100m world record holder, faces a lifetime ban from athletics after testing positive for testosterone in Kansas in April.
His coach Graham said an aggrieved masseur rubbed testosterone cream into Gatlin's legs believing the sprinter had him sacked.
But US track legend Johnson told the Daily Telegraph: "It's a new twist on an old excuse. Graham has no credibility."
Graham told the Washington Post: "We know who the person is who actually did this."
"We are trying to make sure we can prove his [Gatlin's] innocence, and we hope this individual has the guts to come forward and say he did it," he said.
Gatlin has pleaded his innocence since revealing his positive test on Satuday, denying knowingly taking performance-enhancing substances.
But Johnson, a five-time Olympic gold medallist, said: "Graham has had several athletes who have tested positive or been banned from track and field."
"Yet Gatlin has continued his association with Graham knowing it would probably taint him. Even if Gatlin is innocent, he will be suspected forever and is about to see the danger of his continued association with Graham," Johnson said.
Graham, who also coached the disgraced former world record holder Tim Montgomery, was the whistle-blower who launched the Balco steroid investigation in California.
He sent in the syringe to the authorities that sparked the scandal that rocked US athletics.
Johnson added that Gatlin, "with a confirmed A and B sample ... should be banned for life unless he can quickly come up with proof that he did not knowingly take a banned substance."
"Circumstantial evidence produced by Gatlin, his coach and his lawyers that someone else is responsible should not be nearly enough," he said.
"Graham should also be banned for life due to his involvement with an alarming number of athletes who have tested positive while training under him. Unfortunately, there is no rule in place to deal with coaches like him. And until there is, we might continue to see athletes cheating and damaging the sport," he said.
The claim that the person behind the sabotage is allegedly a former member of Graham's training camp staff also met with raised eyebrows by World Anti-Doping supremo Dick Pound and even Gatlin's attorney, Cameron Myler.
"I heard of [Graham's] comments and read them in the press -- they are not authorized by us and we didn't know about them. Trevor's comments were not made with the knowledge or authorization of either Justin or us," Myler told the BBC late on Sunday.
Pound said that Gatlin faced an uphill battle to prove the story to avoid being banned for life as a second-time offender.
"If he can find somebody who did in fact spike it that's for them [the Americans] to prove, but short of something like that he faces a very serious problem," Pound said.
The anti-doping supremo then pointed his finger at Graham.
"Bear in mind Trevor Graham is himself being investigated by the Grand Jury because a surprising number of his athletes have been found guilty of doping offences," Pound said.