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As in Group H, Group G features two teams with seven points in the final game of the group stage.
Celtic and Benfica are tied on points, with the Scottish side hosting Spartak Moscow. The Portuguese side need to match Celtic's result to ensure qualification but must face Barcelona at the Camp Nou.
With Victor Wanyama suspended, all eyes will be on Georgios Samaras. The Greek striker has scored three times so far in the group stage, with one coming against Spartak Moscow on Matchday Two.
Samaras hasn't been great for Celtic domestically this season but has looked sharp in European competition. If Neil Lennon's side wins this game, they will almost certainly reach the knockout stages.