Barcelona made contact a few days ago with the Toulouse defender Issa Diop to find out his plans for the future.
The Blaugrana have been following him for several years and have been keeping a close eye on his progression in Ligue 1.
Diop's a tall centre-back (1.90m), who moves quickly with and without the ball. The 21-year-old is rated at around 25 million euros and there's plenty of interest in him.
He is one of the young French defenders Barça have been monitoring. The club are making plans in case they have to sign a fourth -- or even a third -- centre-back.
For that reason, they contacted Diop. Everything will depend on if Umtiti decides to continue with the club, though, and if Vermaelen remains for another year.
Barça are also alert to the German market. Schalke's Thilo Kehler, 21, has been followed as has Leipzig's Dayot Upamecano.