Laurent Blanc labelled Paris St Germain's Coupe de France exit at the hands of Montpellier "a disappointment but not a disaster".
At the Parc des Princes, Daniel Congre's opener was cancelled out by PSG's Edinson Cavani before half-time.
But Victor Montano restored Montpellier's lead in the 69th minute, and 2-1 was the way it stayed as Rolland Courbis' relegation-threatened side progressed at the expense of the Ligue 1 leaders.
PSG head coach Blanc said on his club's website: "In the first half, we can have some real regrets, both in attack and in defence.
"In terms of how we played, there's not really too much to say about the players, but this is the cup and Montpellier believed in themselves right to the end.
"It's a disappointment but not a disaster. We didn't do what we had to do and we were punished by a Montpellier that made the most of their opportunities."