Wales fought back to consign 14-man Les Bleus to a heartbreaking Rugby World Cup quarter-final defeat in Oita four months ago, but secured a first win in Cardiff for a decade on Saturday.
Clinical in attack and resolute in defence, thanks in no small part to former Wales defence coach Shaun Edwards, France left the Welsh's hopes of winning back-to-back Six Nations titles in tatters.
Anthony Bouthier scored his first Test try and Paul Willemse also went over in a first half that ended with Fabien Galthie's inspired side deservedly leading 19-7.
Wales were just a point behind following a converted Dillon Lewis try, but Ntamack went over for a third France score before the classy fly-half was on target with a second penalty.
Plucking it out of the air...
— Guinness Six Nations (@SixNationsRugby) February 22, 2020
Dan Biggar set up a tense finale with a try he converted to take his tally to 18 points, but Wales - who lost George North and Josh Adams to injury - were unable to complete another stunning turnaround.
Vibrant France are four points clear of Ireland, who play England on Sunday, with three wins out of three representing a dream start to the Galthie era in their quest to claim a first Six Nations title since 2010.
Biggar gave Wales the lead with an early penalty, but France hit the front when Leigh Halfpenny spilled an up and under from Ntamack and the alert Bouthier scooped up the loose ball before scooting away for the opening try six minutes in.
Ntamack stretched the lead to seven points with a second successive kick at goal after North – who was accidently caught by Gael Fickou - failed a head injury assessment.
Biggar's second penalty reduced the deficit before Fickou had what would have been a brilliant try ruled out for a forward Bouthier pass, but Willemse reached out to touch down for rampant Les Bleus following a well-worked lineout move on the half-hour mark.
The ice-cool Ntamack converted expertly and although Biggar split the posts again, France defended for their lives to deny Wales a first try on the stroke of half-time, with Gregory Alldritt in the sin bin for persistence infringements.
Les Bleus lost Cyril Baille with a dislocated shoulder and suffered another blow when Lewis crashed over for his maiden Test try, which Biggar converted to make it a one-point game.
Wayne Pivac's side were in the ascendancy, but the majority of a vociferous crowd were shell-shocked when Ntamack intercepted a Nick Tompkins pass and ran 50 metres to dot down, then added the extras after 52 minutes.
Ntamack maintained his perfect record from the tee to give France an 11-point lead before wing Adams limped off.
France breathed a sigh of relief when Willemse was not adjudged to have deliberately knocked on a pass from Ken Owens with Wales close to the try line, prior to Mohamed Haouas being shown a yellow card with Wales well on top.
Biggar had the French nerves jangling when he finished five minutes from time, but France held on after Matthieu Jalibert pulled a penalty wide with Ntamack off the field after picking up an injury late on.
Ntamack coming of age
Fly-half Ntamack was named man of the match after producing a masterclass in a victory that shows France are the real deal.
The 20-year-old was anything but intimidated in a cauldron of noise, pulling the strings as he showed his outstanding quality both with the ball in hand and with the boot.
His towering kick drew an error from Halfpenny for the opening try and Ntamack read Tompkins' pass superbly before darting away for a crucial third French try.
Edwards effect evident once again
Edwards has not been in his role as France defence coach for long, but the impact he has made was evident once again at a stadium where he celebrated so much success with Wales.
France threw bodies on the line, just as they did in a brilliant win over England on the opening weekend, and stood up to huge pressure applied by Wales.
They attempted 237 tackles to Wales' 146 and won five turnovers, while Wyn Jones' claim they would "cheat" at scrum time proved to be wide of the mark.
Key Opta facts
- France have won their last four Six Nations games, the last time they enjoyed a longer winning run in the Championship was an eight-game streak from 2009 to 2011.
- This was the first time since a clash with Ireland in 2013 that Wales have conceded three or more tries in a home Six Nations match.
- Wales had won seven consecutive home games in the Six Nations before this defeat, it was their best such run in the competition since 1975-82.
France travel to Murrayfield to face Scotland on March 8, while Wales have a fortnight to lick their wounds before a tough trip to Twickenham to do battle with England.
Photo Getty Images Caption: Romain Ntamack scores France's third try