Charlton Athletic winger Ricky Holmes
Holmes played under Blades boss Chris Wilder at Northampton Town, the club from which the Addicks signed him a year ago.
Sheffield United manager Chris Wilder
However, a Bramall Lane reunion does not appear to be on the cards at the minute, after Charlton allegedly warned United that their reigning player of the year is not for sale.
Addicks boss Karl Robinson previously told the South London Press he is hopeful the club will extend Holmes' deal, which is due to expire next summer.
However, should no breakthrough be made soon, it could be in Charlton's best interests to move the player on, being at risk of losing him for nothing otherwise.
United have already added Ched Evans and Nathan Thomas to their League One title-winning side, and Portsmouth left-back Enda Stevens could be next through the Bramall Lane door, the Sheffield Star reports.
Returning Sheffield United striker Ched Evans