A Rodrigo Lima penalty and Nicolas Gaitan goal saw Benfica bounce back from Edinson Cavani's opener to leave them waiting on Olympiacos' result against Anderlecht.
The Greek side won 3-1, with former Benfica striker Javier Saviola netting twice, to shut the door on his former side.
PSG boss Laurent Blanc made eight changes from the team that beat Sochaux at the weekend with full-backs Kalifa Traore and Lucas Digne making their Champions League debuts for PSG.
The match got off to a blistering start as Benfica sought to pile early pressure on an experimental PSG defence.
Goalkeeper Sirigu, one of three PSG players to keep their place, made an acrobatic early stop to keep out Enzo Perez's well-hit 25-yard drive. Sirigu then turned aside Silvio's shot from 12 yards.
PSG were giving as good as they got and Jeremy Menez tested Artur before he needed to punch away a Thiago Motta free-kick.
PSG went ahead on 36 minutes when Cavani from point blank range.
The Uruguayan was flat-footed when Lucas Moura's initial dangerous ball across fizzed across the six-yard box, but could hardly miss when Menez kept the ball alive.
The midfielder did well to reach a ball the Benfica defence appeared to think was headed out and they had no time to react when Menez fired his pall back for Cavani stationed on the line.
PSG's lead lasted just eight minutes, however, after Benfica won a penalty when debutant Kalifa Traore fouled Silvio as they battled for a header.
Lima did not pass up the chance to level as he fired his spot-kick past Salvatore Sirigu despite the goalkeeper correctly guessing to dive to his right.
It was all Benfica in the moments after half-time with Gaitan, Lima and Luisao all missing glorious opportunities.
Gaitan ensured they did not prove costly when he could hardly miss when Maxi Pereira's cross on was deflected into his path on 58 minutes.
Pereira did well to beat his marker and his delivery took an advantageous deflection off a defender for Gaitan to stab in from two yards.
Lazar Markovic missed a glorious chance to wrap up the win but it would not have mattered as Olympiacos won, in a match they missed two penalties and Anderlecht had three players sent off.