Manchester United legend Andy Cole admits they'll struggle to replace Nemanja Vidic.
Vidic has left United for Inter Milan.
"There's always been someone in the past to step in as captain," Cole said.
"You always used to see a natural successor, for example when Steve Bruce left, Roy Keane took over.
"Who's gonna replace Vida because he was a massive presence on the football field and his partnership with Rio was phenomenal. You don't know who will replace him. Rooney has been mooted.
"The new manager comes in with new ideas, but you don't know who he will pick. It's a real toss up for me."
