Didier Deschamps said a virus in the France squad impacted their woeful start to Sunday's World Cup final, though he stopped short of blaming it for Les Bleus' defeat.

France failed to become the first team to retain the World Cup since 1962 as Argentina triumphed in a penalty shoot-out following a remarkable 3-3 draw at Lusail Stadium.

Before Kylian Mbappe's hat trick enabled France to force extra time and penalties, Deschamps' side made a slow start, becoming the first team to fail to attempt a shot in the first half of a World Cup final.

France had been without Adrien Rabiot and Dayot Upamecano due to illness in their semi-final win over Morocco four days earlier, and several other players reportedly experienced symptoms in the days preceding the final.

Asked about the spread of the virus after Sunday's defeat, Deschamps said it played a role in France's lethargic start.

"The whole squad has been facing a tricky situation for a while now, maybe that had a physical and psychological impact," Deschamps said.

"But I had no concerns about the players who started the match. They were 100 per cent fit, but we only had four days since the last match so perhaps there is some tiredness. 

"That's not an excuse but we didn't show the same energy as previous matches and for the first hour we weren't in the match.

"In those first 70 minutes or so, we were playing a very aggressive and dynamic opponent and we weren't at the same level for a number of reasons.

"We managed to come back from the dead and made a magnificent comeback from a very difficult situation."

Deschamps made his frustration with France's first-half performance clear by becoming the first boss to make two substitutions before half-time in a World Cup match when he withdrew Olivier Giroud and Ousmane Dembele.

Despite Les Bleus' failure to clinch the trophy for the third time, Deschamps praised the players he introduced, Marcus Thuram and Randal Kolo Muani, for reviving the contest.

"I went through a lot of different emotions tonight," Deschamps said. "There are some regrets because we were so close to winning but it wasn't to be.

"There were a number of reasons why we had a very strong opponent and we were lacking a bit of energy from some key players.

"We had some young inexperienced players who came on and brought some freshness and quality. They got us back in the match to keep the dream alive."