After Maxence Caqueret had been sent off with 20 minutes remaining, Cherki found the back of the net in the last minute to add to goals by Memphis Depay and Marcelo, putting fourth-placed Lyon on 70 points with three games left.
Monaco, who had opened the scoring through Kevin Volland and levelled for 2-2 in the 86th courtesy of a Wissam Ben Yedder penalty, are one point ahead in third place.
They now trail leaders Lille by five points and second-placed Paris St Germain by four after both won their respective games on Saturday. — Reuters