As it was, Ireland did manage to win at Twickenham, but only by four points, meaning the title went to France on points difference
Outgoing champions Wales had threatened to set up a dramatic conclusion to the tournament by pulling off a surprise win at the Millennium Stadium but Florian Fritz settled the game six minutes from time.
Wales had led 16-11 after a fine performance which included a superb try from Hal Luscombe but Fritz's effort and a later Jean-Baptiste Elissalde penalty killed them off.
France were still not certain of the title but Ireland would need to beat England by a landslide in the final match on Saturday evening to deny them.
Wales were determined to end their reign as champions on a high and took the game to the French early on.
Michael Phillips almost found a way through Les Bleus' rearguard and Stephen Jones took an early chance to give his side the lead with a fourth-minute penalty.
Dimitri Yachvili levelled with a penalty of his own but Wales remained the dominant side, playing the kind of attacking rugby that had been missing for most of their campaign.
They gained the upper hand when hooker Raphael Ibanez was sent to the sinbin after 24 minutes for taking out Robert Sidoli off the ball during a promising Wales attack.
Jones kicked the resulting penalty from in front of the posts and Wales further capitalised on their man advantage to claim the opening try through Luscombe.
Luscombe started the move with a quick break on the left and finished off after Shane Williams was stopped short by a despairing Julien Bonnaire grabbing his shirt.
Jones converted to increase the lead to 10 points but France cut the score back to 13-6 before half-time as Yachvili landed his second penalty.
Sensing their title chances could be slipping away, France were forced to raise their game in the second half but Damien Traille, with Yachvili having been substituted, missed two penalty kicks.
France finally forced their way back into the game as Dimitri Szarzewski barged over from close range after 50 minutes but Wales retained a slender lead as the Traille missed the conversion.
Wales steadied themselves and edged further ahead with a penalty from half-time substitute Gavin Henson.
But France continued to press and Fritz took a well-weighted kick superbly to slide over under the posts with 74 minutes on the clock.
Elissalde converted to put them ahead for the first time and then rounded off the scoring moments later.