It was a big reward for Celtic, who took a giant step into the knockout round last month when they stunned Barcelona 2-1, and they will be appearing in the last-16 for the first time since 2007-08.
Celtic went ahead in the 21st minute with Gary Hooper's low drive after a blunder by Spartak centre back Juan Insaurralde but the Russian side pulled one back six minutes before halftime through Ari's delightful lob.
The hosts, who finish as runners-up to group winners Barcelona, pushed hard for a winner but had to wait until the 82nd minute when Commons struck home from the spot after Giorgios Samaras was pushed over in the area. (Writing by Sonia Oxley; Editing by Alison Wildey)
