Geoff Toovey has refuted allegations Manly were powered by banned substances during their 2011 NRL grand final win.
Darren Hibbert, who has been a central figure in the ASADA investigation, has claimed he supplied inositol, a substance which has similar properties to EPO and is banned in horse racing, to the Sea Eagles during the 2011 season.
"It made the players unstoppable," Hibbert told Channel Nine in a statement on Thursday night.
Hibbert claimed he supplied inositol to players without the knowledge of then-head coach Des Hasler, Toovey, who was Hasler's assistant or any of the club's support staff or the players themselves.
It was unclear why Hibbert had come forward with the claims now.
Speaking on Fox Sports NRL 360 shortly after the claims were aired, Toovey denied the accusations.
"He is missing a few brain cells, he is not all there," Toovey said of Hibbert.
"Our head trainers would not have let him anywhere near anything the players were going to take.
"He was bringing a vitamin or supplement to one of the players that was allergic to the general stuff. But that was a minor thing and it has all been cleared by the league."
Manly defeated the Warriors 24-10 in the 2011 grand final.