Keane, though, has claimed that Ole Gunnar Solskjaer's side should first focus on their defence, with 'one or two players' needed in that area of the field.
The former midfielder also said that he was "not convinced by Luke Shaw", who has been deployed as a third centre-back in matches against the so-called bigger sides this season.
"People always talk about the big clubs needing attacking players. But I still think United need one or two defenders," Keane told Sky Sports News.
"I'm not convinced with the centre-half [pairing], they need another centre-half, and I'm certainly not convinced by Luke Shaw. Brandon Williams has done well as a young kid, even though he's right-footed playing on that side."