Fournier's men threw away a half-time lead as they lost 2-1 at Lille last week but Lyon responded in emphatic fashion at Stade de la Mosson by crushing Montpellier via braces from Alexander Lacazette and Nabil Fekir.
Former Borussia Dortmund striker Lucas Barrios gave hosts Montpellier a sixth-minute lead but Lyon hit back with goals from Lacazette and Fekir approaching the break.
Fekir netted his second with 18 minutes remaining before Corentin Tolisso and Lacazette completed the rout in injury time as Lyon returned to the top of the league standings, one point ahead of reigning champions Paris Saint-Germain.
"It was a bit of a bizarre match, in which we conceded an early goal but kept going and deservedly came back into it," said Fournier.
"We created quite a few chances in the first half. It was a first half of quality, while the second half was more sluggish.
"Montpellier responded, as we could have expected, but at least we didn't see a repeat of last week against Lille. We were a goal up and then conceded two, so we showed that we had learned the lesson from the Lille game and this is great preparation for the trip to Marseille."
Fournier reserved praise for Fekir following the 21-year-old's two-goal haul away from home.
Fekir, who is reportedly being monitored by Arsenal, netted his first of the match in the 40th minute as he played a one-two with Yoann Gourcuff before curling the ball beyond Geoffrey Jourdren.
The French midfielder added his second 18 minutes from time after combining with Gourcuff again to scoop the ball over Jourdren.
"Fekir was good, just like the other attacking players, with Gourcuff and Lacazette," Fournier said. "The six months that Fekir has just had are an accelerated apprenticeship of the very top level.
"It has been difficult for him to take it all in but we have to acknowledge that tonight Nabil looked liberated and that helped us win the match."
