Sunderland are still looking to bring in more players on transfer deadline day.
Having completed the signing of Fabio Borini, Advocaat is now focusing on improving his defensive ranks, having seen the Black Cats struggle to shield their goal this campaign.
The Wearside club have shipped 10 goals in their four Premier League games so far this term, and the report claims that Advocaat is looking at sign a new defender before the close of the window - likely on a loan deal.
Adam Matthews - a summer signing from Celtic - is out injured, whilst Billy Jones, Patrick van Aanholt and Younes Kaboul have all been struggling so far this season, and the Dutch head coach is keen on a new full-back in particular.
A centre-back is a possibility, but following the signing of Kaboul, it is not expected that owner Ellis Short will sanction a deal for another central player.
There are no indications in the report as to any full-backs that Advocaat is looking at, and the head coach will be working overtime today to secure a new signing before the close of the transfer window this evening.