Ahead of the Manchester derby at the Etihad on Sunday afternoon, the Danish legend, who also played for Manchester City, admitted that United's defence is in particular need of improvements.
Speaking to BBC Sport, Schmeichel said: "Louis van Gaal's Manchester United is a work in progress. The signings in the summer were good and very exciting and that gives hope and enthusiasm, but they need to tighten up in defence because conceding so many goals is not going to win you anything.
"The January transfer window is coming up and traditionally United do not buy but I think they have to do that. If they can tighten up at the back then yes, they can make the top four."
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