France claimed a 27-23 victory at the Principality Stadium to make it three wins from three as reigning European champions Wales lost at home in the tournament for the first time since 2017.
But the game was not without controversy as France – leading 27-16 with 15 minutes to go – escaped sanction when second-row forward Paul Willemse knocked the ball down with wing Josh Adams set to take Ken Owens’ pass.
Adams seemed likely to score in the corner, but English referee Matthew Carley decided a penalty was punishment enough and chose not to brandish a yellow card.
“There was quite a few key moments in that game,” Wales head coach Pivac said.
“It just seemed, whenever we were playing advantage, the next ruck was killed or the ball was slowed down so we came back for the penalty.
“There was the (Willemse) slap down. We had a good look at that and I think the officials may have got that one wrong. That killed momentum there as well.
“Another disappointing one was when the French tighthead (Demba Bamba) came on. He went straight across the scrum and was rewarded for that. Those were the big moments in the game.”
Dillon Lewis’ first Test try reduced the deficit to a point, but Romain Ntamack – who finished with a 17-point haul – claimed an interception score and kicked a penalty to put France in command.
Biggar scored a late try, but France held on for a famous win.
“It’s about building, we created a lot of opportunities and I think we are heading in the right direction. It’s about taking those opportunities.
“If we convert one or two more we are truly in games and winning. You come back to the intercept, three v one. If we are accurate with our passing we probably score at the other end.
“That was a big momentum shift. We’re frustrated with a couple of decisions we made ourselves after creating opportunities on one or two occasions.”
Wales lost both wings, George North and Adams, to injury. North went off in the 11th minute and did not return after failing a head injury assessment.
Adams picked up an ankle injury and will be assessed next week ahead of the trip to Twickenham on March 7.
France head to Scotland next before concluding their championship at home to Ireland.
Les Bleus have not won the Six Nations since 2010 – when they last did the Grand Slam – and team manager Raphael Ibanez admitted the Cardiff victory was sweet for defence coach Shaun Edwards.
The Englishman spent 12 years as Wales defence coach under Warren Gatland before joining the France set-up in November.
“Shaun gave so much for Wales for years and we are pleased to have him,” Ibanez said.
“You could feel after the game he was pleased. It was an awesome performance from our defence through the game.”
On whether Wales could have had a penalty try when Willmese knocked on, Ibanez added: “You need to watch the game and review it to think about that.
“We don’t talk about the championship, just the next game.”
Wayne Pivac’s press conference for Wales vs France:
Sign up to our mailing list here and we’ll keep you up to the minute with weekly updates from the world of rugby.