France have moved into pole position for the Six Nations title, withstanding an early Antoine Dupont injury to thrash Ireland 42-27 with a blistering second half that dealt a likely fatal blow to the hosts' hopes of a record third title in a row.

France's hopes in a must-win game looked in trouble on Saturday when Dupont hobbled off after 27 minutes and Ireland led early in the second half.

But three tries in 12 minutes from Paul Boudehent, Louis Bielle-Biarrey and Oscar Jegou left the ill-disciplined Irish stunned and with their grand slam dreams in tatters.

Damian Penaud put the icing on the cake late on by equalling the great Serge Blanco's French record of 38 tries before Ireland flattered the scoreboard with two consolation tries.

The bonus-point victory moves France two points ahead of Ireland and six clear of England, meaning any kind of win over Scotland next week will almost certainly secure Les Bleus their second title since 2010, given their far superior points difference.

Long billed as the likely title decider for effectively the fourth year in a row, it was a predictably breathless opening with Ireland bossing the breakdown, set piece and forcing early penalties but unable to make the pressure count.

The game took its first big swing after 20 minutes when Ireland lock Joe McCarthy was yellow carded for needlessly pulling back Thomas Ramos off the ball. It took France less than a minute to take advantage with a try for flying Bielle-Biarrey.

If Ireland had felt hard done by when James Lowe - one of their players of the tournament - limped off injured in the warm-up, France suffered a nightmare blow of their own when their lynchpin Dupont left with a knee injury.

It also threatened to expose the visitors' high risk, high reward call to pack the bench with seven forwards and just one back but that decision would ultimately pay dividends.

A Sam Prendergast penalty cut the deficit before another sloppy Irish error allowed Ramos to strike right back. The Irish flyhalf, who struggled with kicks from hand, struck another from dead on halfway make the score 8-6 to France at the break.

Ireland brought the momentum into the second period and hooker Dan Sheehan went over in the corner within three minutes to put them ahead.

But Boudehent put France back in front in controversial fashion and Ireland wing Calvin Nash was sin-binned for a foul in the build-up that meant flanker Jegou replacing centre Pierre-Louis Barassi.

That was the cue for France to really turn it on and man of the match Bielle-Biarrey's 11th try in his last seven games was a stunner as he grubber-kicked around Prendergast and won the goal-line sprint.

France then ran riot against a ragged and tired defence as they deployed their forward-heavy bench with makeshift centre Jegou securing the bonus point before the hour mark.

Penaud added his record-equalling try five minutes from time before Cian Healy marked his final Ireland home game and Jack Conan his 50th cap with consolation tries that did little to ease a crushing defeat, only Ireland's second at home in 25 games.