"You will always be interested in someone like him," Redknapp told The Mirror. "He is a great player and can be unplayable at times. He is a great lad and great to work with.
"He was fantastic in that year he had at Portsmouth. The club owe him a massive debt for what he did.
"We bought him for £1million and sold him for £5million. He scored 19 goals and without those goals they would probably have gone down.
"He kept the club going and for me he has been one of the main players for the last six or seven years."