Scottish Premiership side Rangers have tabled an improved £3m bid for Millwall defender Jake Cooper, according to a report.
The Gers are thought to have had an earlier offer rejected for the 23-year-old, who is under contract at The Den until 2020.
Sky Sports News suggests that Millwall remain unmoved in their stance, however, despite Steven Gerrard's side upping their bid.
Cooper featured 42 times for Millwall last season, forming part of the Championship's fifth-strongest defence as the Lions finished just outside the playoffs.
Rangers' interest comes despite already bringing in defenders Jon Flanagan, Connor Goldson and Nikola Katic - three of nine signings made during the off-season.
