Eugénie Le Sommer celebrates after scoring the hotly debated penalty against Norway to all but secure France’s place in the knockout phase of the Women’s World Cup. Photograph: Sébastien Nogier/EPA

Eugénie Le Sommer held her nerve to score a VAR-awarded penalty winner for France after Wendie Renard had potentially gifted Norway a vital point in the race to top Group A but the France manager, Corrine Diacre, said her side had work to do.

“We’re still outsiders,” she said. “We found some difficulties. It’s all about the fine details. Little by little that’s how you become the favourites.”

With France leading Norway courtesy of a Valérie Gauvin effort straight after the break, the six-times Champions League-winning Lyon captain Renard was left clutching her face in anguish as she scored an own goal from close range without a white shirt in sight.

But after Ingrid Engen was penalised for catching Marion Torrent, Le Sommer made no mistake and the hosts have two wins from two.

The Norway manager, Martin Sjögren, thought his team were “equal” to France and said it was “impossible” for players to hold back from tackles following the VAR incident in which Engen seemingly got the ball. “I need to see it again. I think we were punished a bit but I’m not sure if it was a penalty or not to be honest with you,” he said. “It’s kind of hard to tell a player to hold back, I haven’t seen the situation so clearly so I need to see it again to say wither its a foul. But the referee says it is. It’s hard to tell a player to hold back, that’s going to be quite impossible.”

If frustration from the local population over the enforced online-only ticketing system led them to stay away when England played Scotland here, it was a different situation with the hosts in town. After their clinical 4-0 defeat of South Korea in Paris last Friday, 6,000 tickets were sold the following day to make Nice an official sellout – though there was still a substantial number of empty red and white seats littered throughout the stands.

The home nation’s opponents were, on paper at least, their trickiest Group A test. Norway are a competent side, despite the absence of Ada Hegerberg, the scorer of a hat-trick for Lyon in the Champions League final, because of her unhappiness at the state of the game in her homeland. The centre-back pairing of Chelsea’s Maria Thorisdóttir and Maren Mjelde may not be how they line up for their club but, despite at times a sense of desperation in their play, they held strong against the early French assault.

The Norway players express their dismay at the award of the decisive penalty. Photograph: Jean-Paul Pélissier/Reuters

Kristine Minde struggled to contain Kadidiatou Diani, with Guro Reiten doing little to help out the full-back behind her. Three times in 15 minutes, and twice in quick succession, the France winger sped past Minde and whipped a dangerous ball into the box but each time Gauvin was unable to capitalise.

Norway’s best chance fell to Engen. Amel Majri was dispossessed by Karina Sævik on the right and she swept it into the path of Caroline Graham Hansen, who forced a corner. Engen got her head on the delivery but Majri cleared at the near post to atone for her earlier error.

If France were frustrated and the crowd restless, it took just one minute after the restart before the latter erupted into life.

Le Sommer, scorer of the tournament’s opening goal, turned provider, whipping a cross towards Gauvin, who swept in from close range. A stadium awash with mobile phone lights and miniature flags was suddenly re-energised. For Gauvin, it was relief.

“I’m overjoyed with the result, Gauvin was in a little bit of difficulty in the first half but in the second half it was more interesting. I wanted to show she could give a lot to this team but it’s not going to stop there.”

If momentum was with France it was a calamitous error from two-goal hero against South Korea that would level things. Isabell Herlovsen broke down the left and put a cross across goal. Renard, without a Norway player near her, placed the ball into the bottom corner from six yards out.

Mistakes are what Diacre wants to eliminate. “We are working on certain aspects of the game,” she said when asked if she had learned anything new about her players. “Errors we can erase, individual or team that we’d like to get rid of as we move forward.”

Mistakes seemed to be the order of the day, though, and Engen’s high foot painfully caught Torrent on a thigh. It went to a VAR review, before Le Sommer stepped up to render her Lyon teammate’s error meaningless. France passed the test, just.