Southampton is hoping to make Toby Alderweireld's stay permanent. Alderweireld came over on loan from Atlético Madrid on the final day of the summer transfer window and has been a critical part of their defense.
Alderweireld joined Atleti for roughly £5 million from Ajax in September 2013.
Diego Simeone already had Diego Godin and Miranda playing central defense, which would have limited Alderweireld's appearances.
There is concern for Atleti that bigger clubs will target Godin and Miranda.