With the Ligue One holders third in the current table, Sow has paid tribute to Cole's contribution.
The Senegal striker admitted: "He's a great pro. Along with another of our players, David Rozehnal, he is the first in the locker room in the morning.
"He is always there ready, he is very involved and highly motivated, even when he's not playing. It's a surprise to see him like that.
"It was a gamble for the club, but so far it has been a success."