The left-back department at the Stadium of Light has been a constant worry for Gus Poyet this summer, who currently has no senior players on his books able to fill the position.
Following Filipe Luis's arrival in West London, the 23-year-old defender confirmed last week that his time at Stamford Bridge was coming to an end, and that he would be on the look out for a new club this summer.
The Dutch International has only ever made a handful of appearances for Chelsea after first breaking into the first team in 2009, since then the defender has been loaned out to a string of teams, and has spent the last two seasons at Vitesse.
Gus Poyet spoke yesterday regarding his frustration at the lack of transfer activity at the Stadium of Light, and stated his intention to recruit at least one new player before his squad jets out to Portugal for their pre-season tour tomorrow.
Van Aanholt has only one year remaining on his current deal at Stamford Bridge, and could be being sold for a knock-down price.
Poyet has made no secret of the fact he hopes to bring last season's loan sensation Marcos Alonso back to the club, but with Fiorentina currently holding firm, the Sunderland manager is clearly feeling the pressure to act fast.
However it's unlikely that the 46-year-old will give up in his pursuit of Alonso, meaning Van Aanholt is probably being targeted as competition for a place rather than a direct alternative to the Spaniard.