Rennes seal Grenet deal
Grenet was a peripheral figure for The Rams last term, so Derby chief John Gregory sent him out to Rennes in order to remove him from the wage bill.
The player started brightly, but has been on the sidelines in recent weeks with a calf injury.
A permanent deal was set to be concluded when Grenet made 20 appearances, but his injury meant that would not be able to happen until the summer.
Rennes have been impressed with the defender and contacted Derby to discuss pushing through a deal before the transfer deadline closed.
The Rams were only too willing to do business, and agreed a deal with Rennes paying a fee near to the £1 million mark.
Grenet has penned a three-year deal with Rennes and will hope to help them avoid relegation from Le Championnat when he returns to fitness at some point in March.