Roma coach Luciano Spalletti admitted it is vital his side come away from their games against Sporting Lisbon with the points.
The Italians completed half the job on Tuesday night by beating Sporting 2-1 at the Stadio Olimpico in UEFA Champions League Group F.
Spalletti is aware Roma must come out on top against Sporting to progress from a group which includes Manchester United.
"These two meetings are decisive for advancing," he said.
"The guys went out onto the field very focused tonight. They're a good team, but we conceded very little."
Mirko Vucinic scored the winner for Roma against Sporting Lisbon after coming on as a substitute for the injured Francesco Totti.
Totti injured his right ankle early on in the game and was forced off in the 35th minute after trying to continue.
Spalletti added: "We'll have to see tomorrow what the extent of it is."