Justin Gatlin's masseur has denied allegations that he was responsible for doping the world and Olympic 100m champion with a doctored cream.
Gatlin says he cannot account for his positive test for testosterone
Gatlin faces a life ban from athletics after testing positive for testosterone at a meeting in Kansas last April.
His coach Trevor Graham claimed that Chris Whetstine had put the cream on Gatlin at the Kansas Relays.
But Whetstine said: "Trevor Graham is not speaking on behalf of Justin Gatlin and the story about me is not true."
Whetstine, who has worked as Gatlin's masseur for much of the past three years, added: "I have fully co-operated with the investigation into this matter."
Graham said Whetstine had been upset with Gatlin because he thought the sprinter was responsible for him being fired earlier this year.
It's a new twist on an old excuse - Graham has no credibility
Athletics legend Michael Johnson
Whetstine was later reinstated and has travelled with Gatlin to meets since April, the coach said.
Graham said Whetstine had applied a whitish cream to Gatlin's groin area and the back of his knees after the Kansas Relays.
Graham said: "When I asked what is that? He (Whetstine) said, 'Get away.'
"He then put it (a tube of the cream) in his pocket."
Graham said he asked Gatlin if was he having problems with his groin area and his knee.
"He said, 'No,' so I dropped it," Graham added. "I have never seen that cream after that."
Athletics legend Michael Johnson has already rubbished Graham's claims.
He said: "It's a new twist on an old excuse. Graham has no credibility.
"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."
Gatlin has denied knowingly taking performance-enhancing drugs and says he will work to clear his name.