The 26-year old scored both Leeds goals in the 2-2 draw at White Hart Lane and prior to the replay at Elland Road on Wednesday night, Redknapp said he could be a force for whichever top flight club is keen on him.
"I believe he could leave on a free transfer at the end of the season and someone has probably done a deal for him already instead of paying £2m for him now," the Spurs boss said.
"He may not be going to Man United or Chelsea, but he's likely to interest clubs who can afford to wait and take him on in the summer for free.
"Leeds are a good side who are capable of playing way above the level they are at now, and even though we should have had the tie wrapped up in the first game, they played very well at White Hart Lane."
Redknapp admitted the match would be no walkover for Tottenham as he expects a determined Leeds outfit to show in front of their home fans.
"I'm expecting a difficult night at Elland Road, although I can't believe it will be more intimidating than it was when I faced Leeds as a player. That team including Norman Hunter, Billy Bremner, Jack Charlton and Johnny Giles was one of the great football sides, up there with the best I've ever seen."