On at least two occasions already, Jason Giambi, the disgraced Yankees slugger attempting a comeback after admitting to a grand jury he took steroids earlier in his career, has called Jose Canseco “delusional.”

Canseco, also known as “The Chemist” who claims he introduced Giambi to performance-enhancing drugs in his new book “Juiced,” bashed back with both barrels yesterday at a signing in New Jersey when he said without steroids, Giambi has no chance to succeed and be the player he once was.

“I don’t think so,” Canseco said. “We saw the decline last year and either he will have the same year power-wise or less.”

Giambi, who hit the field for the first time yesterday in Tampa, hit 12 home runs in 80 games last year.

Canseco added that “in time,” Giambi’s notion that he’s lying will be proven wrong.

“And then you’ll never ask me that again,” Canseco said.