The Saints have contacted Atletico Madrid to discuss the future of the Belgium international, and are keen to beat Arsenal to his signature.
Alderweireld – who represented his nation at the World Cup this summer – only joined the La Liga champions last summer, but his debut campaign in Spain was a forgettable one.
The 25-year-old managed just 16 appearances for the Rojiblancos, and his fate has not been any better so far this term with Diego Simeone having not picked him once since the squad returned from their holidays.
With Atleti chasing Daniel Agger of Liverpool, the classy defender is free to leave for around £6m and has been linked with Arsenal.
But now Southampton have contacted the Madrid side to discuss a deal.
Southampton have contacted Atlético Madrid about Toby Alderweireld, who wants to move to the Pr. League. Also Monaco are interested #saints
— Kristof Terreur (@HLNinEngeland) August 25, 2014
Ronald Koeman is desperate to get in a replacement for Dejan Lovren, with Alderweireld seen as a good option.
The South Coast club will face competition from French heavyweights Monaco, but the player’s desire to switch to the Premier League may be a big factor.
Arsenal may also opt against a move with reports claiming that Kostas Manolas is Arsene Wenger’s top target.