The second-tier hosts took a shock lead 15 minutes in and managed to hold onto their slim advantage despite the late dismissal of Jamel Ait-Ben-Idir.
Cristiano drew a line under his recent poor performances by hitting five for a much-improved Real Madrid in their 9-1 demolition of Granada.
The Portuguese attacker has been criticised for his lack of goalscoring in 2015 but smashed almost half a dozen past Granada in Real Madrid's 9-1 triumph on Sunday.
The San Siro boss is keen to strengthen his squad and refused to deny interest in the Argentine, but rejected reports that Yaya Toure is set to sign.
The forward scored his fifth goal in as many games to keep his side in fourth spot, five points adrift of leaders PSG.