Chelsea were twice denied by the woodwork after Andre Schurrle, on for the injured Eden Hazard, gave them the early goal they wanted in the Champions League quarter-final second leg.
The Blues, 3-1 down from the first leg, suffered a setback when talisman Hazard limped off after 18 minutes at Stamford Bridge.
But his replacement struck 14 minutes later, scoring with a half-volley from near the penalty spot after Branislav Ivanovic’s long throw had been flicked on by David Luiz.
Paris St-Germain, without sidelined striker Zlatan Ibrahimović, moved the ball around nicely and looked assured at the back before leaving Schurrle unmarked.
The German duly punished them – unlike Gary Cahill, who missed a chance to put Chelsea level on aggregate when he blazed high and wide of the target after PSG had failed to deal with Frank Lampard’s left-wing free-kick.
Chelsea continued to push forward after the interval, with Schurrle and Oscar hitting the bar in quick succession early in the second half.
Schurrle was unlucky after being picked out by Willian, while visiting keeper Salvatore Sirigu got nowhere near Oscar’s thumping free-kick.
Chelsea: Cech; Ivanovic, Cahill, Terry, Azpilicueta; Luiz, Lampard; Willian, Oscar, Hazard (Schurrle 18); Eto’o.
Subs: Schwarzer, Cole, Kalas, Mikel, Ba, Torres.