After Northern Irish right-back Trai Hume signed a four-and-a-half-year deal with the Black Cats, bringing in another striker is now the priority for head coach Lee Johnson.
Sunderland are also short of options in central midfield and are in the market for another playmaker.
An additional centre-back may also be needed if Frederik Alves, as expected, returns to parent club West Ham.
We have taken a closer look at some of the players Sunderland have been linked with this month and the chances of them moving to Wearside:
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An additional centre-back may also be needed if Frederik Alves, as expected, returns to parent club West Ham.