The fragility of Sunderland's defence was one of the hot topics earlier this season, particularly after they were thumped 8-0 at the hands of Southampton.
Since then, Gus Poyet's side have tightened up at the back. Save for the 4-1 defeat by Manchester City, who had a red-hot Sergio Aguero that night, Sunderland have conceded just three goals in the other seven games since replacing Vito Mannone with Costel Pantilimon in goal.
With four clean sheets in those seven games, Sunderland are making strides defensively - but that seemingly won't stop Poyet pursuing new defensive reinforcements.
The 25-year-old is currently plying his trade with Reading in the Championship having made a £2.5m switch from Nottingham Forest back in 2012, recovering from an uneventful two-year spell with Tottenham Hotspur after breaking through with Cardiff City.
Sunderland have so far used Santiago Vergini at right back despite the Argentine largely being a centre back by trade, with summer signing Billy Jones making little impact so far.
Gunter would help solve their problems in the position, but they aren't alone in pursuing Welsh international Gunter. According to O'Rourke, Wolverhampton Wanderers are also hoping to sign Gunter in January, meaning Sunderland may have to move quickly to secure his signature - even if a Premier League move is surely more enticing.