Chelsea have reportedly made contact with the agent of Wolfsburg defender Ricardo Rodriguez over a January transfer.
The Swiss left-back has been heavily linked with Arsenal in recent weeks, while French giants Paris Saint-Germain are also thought to have shown an interest.
According to The Sun, however, Chelsea are the side leading the way for the 24-year-old's signature in a deal that could be worth in the region of £21m.
Blues boss Antonio Conte is said to be hopeful of strengthening his backline for the second half of the season, with Rodriguez being seen as the ideal player to challenge Marcos Alonso - and the more versatile Cesar Azpilicueta - for a wing-back berth at Stamford Bridge.
Arsenal are also understood to be on the lookout for new options at the back due to the uncertain future of squad player Kieran Gibbs, whose contract expires at the end of the season.