Rashford meanwhile, has been played out of position on the wings.
Despite United’s over-reliance on the Swedish hitman, they are sixth in the Premier League table, four points off fourth-placed Manchester City.
Mourinho is expected to be heavily bankrolled in the summer window to transform his side into title contenders.
Could this be Jose Mourinho's Manchester United side next season?
Fri, March 31, 2017
Could this be Jose Mourinho's Manchester United side next season if he secures all his summer signings?
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How could Jose Mourinho's side look next season?
Zlatan Ibrahimovic's future at Manchester United remains unclear
Martin Keown is convinced Jose Mourinho needs to sign a striker in the summer
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brahimovic does a lot of talking, but he does miss a lot of chances
And Keown insists that the Portuguese tactician faces a tough decision as to whether to persist with Ibrahimovic up front or to play Rashford in a central striking role.
“The debate will start now about Zlatan [Ibrahimovic],” Keown told the Daily Mail.
“He’s basically all they have. But does he become Rooney next campaign?
“Does he just play a bit part? Do they play Marcus Rashford down the middle? Do they go out and buy?
“They create enough chances, they just aren’t taking them. Ibrahimovic does a lot of talking, but he does miss a lot of chances.
“He has done well, and there is a lot on his shoulders, but you would expect United to go and buy in that area.
“There needs to be that marquee signing in that area.”
United face Sunderland on Sunday (1:30pm).