The former Manchester United captain feels the decision to leave the striker on the bench for the visit of Real Madrid may spell the end of his career at the club
The England international started in the first-leg of the last-16 tie at the Bernabeu, but was left out of the starting line-up for Tuesday's decider, with United boss Sir Alex Ferguson stating that Danny Welbeck was the better option from a defensive standpoint.
Ferguson told ITV: "Xabi Alonso controls the game for Real Madrid. Danny Welbeck is the best at [tracking back] in our team, plus he can work from there to support Robin van Persie."
However, Keane, who spent 12 years under the stewardship of Ferguson at Old Trafford, feels the decision to bench Rooney was not purely tactical and that the former Everton man may be soon be moving for pastures new.
He said: "It surprised us all that he [Ferguson] left Wayne Rooney out. Maybe the writing is on the wall for him.
"Wayne needs a game or two, to be honest. He did okay in the second half against Norwich, but he needs a game."