Reading reportedly dispatched scouts to observe Rennes' clash with St Etienne last weekend.
It remains unknown who Steve Coppell's men were sent to watch, although the club have been previously linked with John Mensah.
The Royals were keen to bring the Ghana international to The Madejski in August, but the newly-promoted outfit failed to secure the 23-year-old's services.
Although Rennes rejected Reading's bid last August, Coppell's side may be ready to test their resolve with a fresh bid in the transfer window.
Ajax and Bayern Munich also dispatched scouts to Stade de la Route-de-Lorient, although, again, the subject of their interest remains unknown.