Mane double helps Al-Nassr close on leader
Cristiano Ronaldo had given the hosts the lead from the spot, setting them on their way to a dominant victory.
After a slow start, Jean Seri was penalised for a handball, and Ronaldo made no mistake from the spot. After a stuttering run-up, he coolly slotted his strike into the bottom-left corner.
Mane got his first on the stroke of half-time, latching on to Ronaldo's pull-back before firing his low shot into the far side of the net.
He could have had a hat-trick, having also hit the woodwork and squandered a first-time shot by slicing it wide, but he did get his second in the 71st minute, guiding Nawaf Bu Washi's cross past Gaetan Coucke.
Cristian Tello came closest to a consolation for the visitors, smashing a long-range effort off the crossbar.