Former Manchester City goalkeeper Eric Nixon says Joe Hart will be the difference in the title battle with Manchester United.

Hart, in Nixon's expert eyes, is head and shoulders above his United counterpart David de Gea.

Nixon, who has just penned a new book "Big Hands Big Heart" about his life, told the Daily Star: "Without doubt, Joe is the best young keeper in the world.

"He's made fantastic saves this season in big, big games.

"It's with Joe in mind that I look across to David de Gea and, if I'm honest, he's still got an awful lot to learn.

"It's not his fault that he cost them £17million but he's not yet got the physical attributes needed for the tough life of the Premier League.

"He's not got the strengths to stand up to the physical presence of opponents. "David needs to be more aggressive and in my mind he's too lightweight.

"He's getting kicked around even though the likes of Rio Ferdinand are obviously trying to protect the lad.

"He's got to get into the gym like Joe and really build up his body.

"One for the future, definitely, but there's still a lot for him to learn in a crucial, nerve jangling run-in to the Premier League title."