Younes Belhanda's cheeky penalty put the French champions in front after nine minutes after Thomas Vermaelen was adjudged to have fouled him just inside the area.
The home crowd were silenced after 16 minutes when Lukas Podolski beat keeper Geoffrey Jourdren after being set up by former Montpellier favourite Olivier Giroud.
Two minutes later Gervinho put the visitors ahead from close range after a low cross into the area by Carl Jenkinson.
Montpellier pushed for an equaliser after the break and had several chances but the closest they came was when Remy Cabella's fine lob struck the woodwork just before the hour.
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