The Black Cats have just seen striker Ellis Simms recalled to Goodison Park by Everton, the Toffees triggering a clause in his loan, and are now a hitman down.
Losing Stewart would be a huge blow, but the Scottish striker is a man in demand amid no new contract yet having been agreed.
Now Brentford are also eyeing Stewart and they are making intense checks on the striker.
The Premier League side may need to enter the transfer market to sign a new striker, especially as they wait to hear about a possible ban for hitman Ivan Toney.
Stewart has grabbed eight goals in just ten Championship outings for Sunderland so far this season.
He missed a chunk of the campaign through injury, but has now returned and scored in Sunderland’s last three league games.
Brentford are likely to keep an eye on how Stewart fares on New Year’s Day when Sunderland take on Blackpool in the Championship.
