Dick Advocaat is reported to be eyeing a move for Belgium defender Nicolas Lombaerts.
Sunderland are in talks with Russian side Zenit St Petersburg over a move for the international defender, who is well-known to the Dutch head coach, according to reports today.
Lombaerts, 30, joined Zenit in 2007, when Advocaat was manager and he won the league in his first season at the club.
They have also worked together when Advocaat was in charge of the Belgium national team.
Strengthening the Black Cats defence is a priority for Advocaat, who made Sebastian Coates his first summer signing.
The defender, who was on loan at Sunderland last season, has signed a four-year contract.
Meanwhile, Sunderland are also reported to have stepped up their bid to sign Holland star Jeremain Lens.
Dynamo Kiev striker Lens is a player Advocaat knows well from their spell at PSV Eindhoven together and Sunderland could look to tie up a £8million swoop in the next week, as previously reported by the Echo.
The 27-year-old operates on the left wing or through the middle and is seen as an ideal option for Sunderland.