Nasri's first goal of the season -- also his 50th for an English club -- and an assist for Pablo Zabaleta secured a 2-0 win for City away against Roma and saw them qualify for the knockout stage at the expense of the Italian side in Wednesday's final round of group games.
Meanwhile, Group E winners Bayern Munich's 3-0 victory at home to CSKA Moscow gave Roma the consolation of a spot in the Europa League.
Zlatan Ibrahimovic had given PSG the lead, but Lionel Messi equalised and, after Neymar paved the way to victory, Luis Suarez added a third -- his first at the Camp Nou since his move from Liverpool -- in the second half.
Barca's victory means they can surely now expect an easier tie when the draw is made on Monday, while the result ended PSG's record of being the only unbeaten side left in the major European leagues this season.
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Schalke's qualification makes it the second successive season that all four German representatives have made it through to the last 16, Borussia Dortmund and Bayer Leverkusen also having progressed.
- City overcome absences -
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Manchester City made light of missing three key players -- leading scorer Sergio Aguero and captain Vincent Kompany were injured while Yaya Toure was suspended -- as the mercurial Nasri showed his positive side.