O'Neil worked with Grant when he was technical chief at Portsmouth and said: "I did a lot of individual work with him which was very beneficial to me.
"We worked on a lot of technical aspects, especially movement on and off the ball.
"He gave me a great insight into the finer details of the game."
He added: "Of course Harry Redknapp was in charge so Avram wasn't getting involved heavily. It was difficult for him to do too much but he picked out individuals and luckily I was one.
"He certainly knows his stuff. And despite what people may say about him and how he comes across, Avram was great company.
"A lot of Pompey players thought exactly the same."