Substitute Edinson Cavani scored with four minutes remaining as holders Paris Saint-Germain beat Saint-Etienne 1-0 in the Coupe de la Ligue round of 16 on Wednesday.
Zlatan Ibrahimovic hit the crossbar with a brilliant volley in a first half that produced few other clear opportunities.
PSG had most of the play at Parc des Princes, but had to wait until late on to score the decisive goal when Cavani's first-time finish from fellow substitute Angel di Maria's cross won the match to seal a place in the quarter-finals.
Laurent Blanc's men are now unbeaten in 20 domestic matches this season and knock Saint-Etienne out of the competition for the third consecutive year as they look to win a third consecutive Coupe de la Ligue crown.
PSG made eight changes to their team, with captain Thiago Silva, Adrien Rabiot and Ibrahimovic the only players to keep their places following the thumping win over Lyon. Likewise, Saint-Etienne shuffled their pack, with Christophe Galtier making nine alterations.
With much-changed teams, it took both sides some time to find their feet as a quiet opening to the match saw Benjamin Corgnet drill a shot wide for the visitors in the only early attempt of note.
It was Ibrahimovic who brought the tie to life with a brilliant effort. Ezequiel Lavezzi's cross from the right was only headed partially away by Nathan Dekoke and the Sweden international unleashed a stunning acrobatic volley that bounced away off the frame of the goal.
The hosts began to threaten more from then on, with Rabiot having a powerful long-range shot saved by Jessy Moulin at the second attempt, Lucas Moura prodding a shot wide and Ibrahimovic off target with an ambitious free-kick as the first half reached a goalless conclusion.
Ibrahimovic had a penalty appeal turned down early in the second half as his run into the box after a neat one-two with Marco Verratti was halted by contact from Ronael Pierre-Gabriel.
Blanc made two changes on the hour mark as he attempted to find a breakthrough, with Ibrahimovic and Verratti replaced by Di Maria and Cavani.
And the two substitutes combined when the former Manchester United midfielder's floated pass was volleyed over by Cavani as PSG continued to struggle to test Moulin, despite dominating possession.
The hosts did just that with 15 minutes remaining when another chance created by Di Maria saw a left-footed Lavezzi drive force the away goalkeeper to make a strong one-handed save.
Saint-Etienne had barely threatened going forward, but they almost sealed a huge upset late on when Hugo Roussey latched on to Corgnet's pass and saw his shot sharply saved by Salvatore Sirigu.
But the visitors' hearts were broken by Cavani. Di Maria's impressive cameo continued with an outstanding high pass from the right, finding the Uruguay striker in his stride to slot a first-time side-footed effort into the far corner - his 13th goal of the season.
