A first-half penalty miss from Diego proved costly as the Frenchman's second half header sees the capital club provisionally move to the league summit
The visitors worked hard to stifle Les Parisiens' rhythm throughout but Gameiro's strike ensured PSG's victory. The recently-promoted side had the opportunity to take the lead from the spot late in the first half, but a brilliant Sirigu save denied Diego from 12 yards out.
The hosts opened the match in unconvincing fashion, with Christopher Glombard twice allowed to cut inside from his left flank. His first venture saw the ball eventually cleared by PSG's congested defense, while the second led to had to Kossi Gassa parrying the the Frenchman's effort.
PSG's Maxwell, shifted to a midfield role for the night, should have opened the scoring for his side after being put through by a delicate through ball from Ibrahimovic. The former Barcelona man failed to put power behind his strike however, and Gassa collected calmly.
Carlo Ancelotti's charges grew in confidence as the first half wore on, dominating possession but failing to find penetration through the middle of the field. The central midfield duo of Alex and Maxwell often resorted to long balls in an attempt to break forward, restricting Les Parisiens to long range efforts.
And it was a lofted ball that presented Ibrahimovic with the chance to put his side ahead, Silva finding his former Milan team-mate with a well-weighted pass. The Swede was unable to direct his volley on target however, firing wide from a tight angle.
Gameiro came inches form finding the breakthrough minutes later, after Nene had put the Frenchman through with a classy backheel. The forward could only direct his strike straight at Gassa, with the deflection cleared off the line by Anthony Webber.
Reims were handed a glorious chance to take a lead into the halftime break, with the referee awarding the visitors a penalty following Gregory van der Wiel's handball in the area. Diego stepped up to the spot, but a brilliant save from Salvatore Sirigu kept the sides level.
Both sides ramped up the pressure with the interval looming, but failed to find a breakthrough in the closing stages of the first half. Alex failed to tap in a curling free kick with only the keeper to beat, before Mamadou Sakho put his body on the line at the other end to deny Glombard.
The second half picked up largely where the first left off, with a dynamic showing from the visitors stemming PSG's rhythm. The hosts were largely restricted to aerial forays, with Sakho making a mess of a header he should have converted minutes after the break.
Blaise Matuidi then found himself in acres of space in the area following a poor corner clearance from Reims, but the midfielder could only direct his scrappy effort at the crossbar. The Frenchman then saw a drilling effort deflected by his own teammate, when the ball appeared to be heading for goal.
PSG was rewarded for its dominance in the 65th minute, when Gameiro latched on to a Maxwell delivery from six yards out. The Frenchman's powerful header left Agassa helpless, and handed his side the lead they and been probing for.
The hosts continued to push for a second in the closing stages, but continuously lacked the final pass to forge opportunities of note. Ibrahimovic's backheel was very nearly controlled by Menez in his stride, after the former had been denied a headed chance by Gameiro's intervening and ineffective contact with the ball.
Ibrahimovic and Menez both had opportunities to put the tie to bed in the opening exchanges, but both failed to beat Agasse from narrow angles. Julien Toudic then saw a scissor kick fly just over at the other end, denying the Frenchman what would have been a spectacular equalizer.
The win sees PSG provisionally draw level with league leaders Marseille, who travels to Troyes later in the round.
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