And the Sunderland boss will no doubt be taking a look at the league above and players who have fallen down the pecking order at their parent clubs.
So which defenders are currently out of favour at their Championship clubs, and could they prove to be realistic targets for Sunderland?
We take a look at some potential options – simply scroll down and click through the pages to see who could be available:
1. Tom McIntyre
The versatile Scottish defender has appeared just three times for Reading this season, and could be available for a loan move before the window closes. Photo: Alex Burstow
2. Romoney Crichlow-Noble
The left-back spent much of last season on loan with Hartlepool United, but has been in and around the Huddersfield first-team squad over the summer. Could a move to League One be the next step? Photo: FRANK REID 2019
3. Greg Cunningham
Another left-sided defender, Cunningham has featured just three times for Cardiff City this season and may be a player on the radar of a host of clubs. Financially, though, this could prove a tricky deal to do. Photo: Clive Brunskill
4. Murray Wallace
The Millwall centre back is yet to start in the league this term, and would undoubtedly be a fine capture for any League One club. Whether Millwall would allow him to leave is a different question, though. Photo: James Chance