Ireland avoided a quarter-final against New Zealand by beating France 24-9 at the Millennium Stadium, but it came at a huge cost.
Joe Schmidt's side will likely be without Paul O'Connell, Jonathan Sexton, Peter O'Mahony and Sean O'Brien for their quarter-final against Argentina next Sunday after a brutal encounter.
In front of a huge Irish crowd, tries from Rob Kearney and Conor Murray were enough for the Six Nations champions, who produced their best performance of the tournament so far, but the losses will be of greater concern.
A bone-shuddering first half saw Ireland lose possibly their two most important players, with Sexton lasting just 25 minutes, while O'Connell was stretchered off at half-time after twice trying and failing to walk off under his own steam.
They will likely be without O'Brien as well as after he threw a vicious punch to Pascal Papé's ribs off the ball at the very first ruck while in the second half O'Mahony was also carted off.
Try-scoring chances were few and far between in the opening 40, with Keith Earls missing the best opportunity of the half when he couldn't hold on after Tommy Bowe had gone clean through.
Instead two penalties from Sexton and one from replacement Ian Madigan were enough to have Ireland up 9-6 at half-time, with Scott Spedding slotting two for France.
After the break Rob Kearney got the game's first try, and in such an attritional affair, an eight-point lead was always going to be too much to recover from.
While France did get back to within a score, a second try, from Murray, sealed the win for Ireland, who will have an extra day to prepare for their clash with Argentina next Sunday which should test their depth.
France meanwhile, will take on New Zealand in Cardiff in a repeat of the 2007 quarter-final. While All Black fans will be understandably nervous, on this form les Bleus won't manage another upset having barely looked like scoring a try.
It was a ferocious start with both teams flying into the tackles and Papé feeling the effects at the very first ruck. O'Brien appeared to be after some retribution for Papé's indiscretion on the last meeting between the two teams and will surely be cited as a result.
While Ireland were winning the collisions, they conceded a couple of early penalties, the second in a kickable position but Frédéric Michalak's strike wasn't clean and the ball fell short.
Les Bleus had a second chance to take the lead when Ireland collapsed a scrum just short of halfway. For the longer range kick, Spedding took over kicking duties, but his effort came back off the post.
Ireland, on the other hand, had no such problem from the kicking tee, Sexton giving them a 3-0 lead on 12 minutes when Mathieu Bastareaud was caught offside tracking back from a chip over the top that Eddy Ben Arous couldn't collect.
Still, France were enjoying more of the territory, and when Michalak ghosted through a gap in the Irish midfield they were in behind. A messy ruck saw the move break down but Ireland were quickly isolated and this time Spedding found the target to level the scores from halfway.
In a tight first quarter, Ireland moved back in front thanks to a second Sexton penalty, with Yoann Maestri the man penalised for rolling away too slowly.
France were soon back on terms with a high tackle on Guilhem Guirado giving Spedding a second chance from long range, knocking one over from inside his own half.
During the week France had talked about targeting Sexton, and he lasted just 25 minutes. Having already taken one big hit on a French attack, Louis Picamoles delivered the final blow with a thumping tackle.
Ian Madigan replaced him and was quickly called into action for a tackle off the ball, putting the Irish back in front 9-6.
Just after the hour Ireland had the first real try-scoring opportunity after Bowe was put clean through off a lineout. The simple two on one should have seen Earls over but he couldn't collect the final pass.
A break from Spedding had France in great position just before the break but they couldn't capitalise. O'Connell was injured in the build-up, replaced by Iain Henderson at half-time.
The first chance of the second half went Ireland's way, Robbie Henshaw going straight past Mathieu Bastareaud in midfield and being stopped just short. While that attack was stopped when Noa Nakaitaci knocked on in a tackle on Murray, Ireland soon broke through with Rob Kearney finishing after the resulting scrum. Madigan missed the conversion but Ireland led 14-6 with half an hour remaining.
It appeared to be the knockout blow, with France struggling for territory, and when Thierry Dusautoir knocked on just outside his 22, it was hard to see a way back for les Bleus.
There was still plenty of time remaining, and Ireland's next casualty was O'Mahony, who also needed lengthy treatment before being stretchered off after coming off second best when carrying at Papé.
France got back to within a score with a penalty from replacement Morgan Parra, and got themselves in good position with ten minutes remaining only for the scrum-half to knock on when O'Brien fell into him in a ruck.
That was the end of France's challenge, and Murray delivered the final blow when he pushed the ball up against the side of the post for Ireland's second try. Madigan converted and the fight went out of France, conceding two scrum penalties as the Irish took complete control in the dying seconds.
Man of the match: After missing the first two games of the tournament, Robbie Henshaw has come back with a bang. It was his break early in the second half, standing up Mathieu Bastareaud, that put Ireland in position for their first try.
Moment of the match: Ireland's troubles began when they lost Sexton to injury just 25 minutes in. Louis Picamoles' hit was perfectly legal but having already been shaken up, Sexton was out for good.
Villain of the match: It's hard to imagine a Joe Schmidt side deliberately targeting an opposition player but that's what Sean O'Brien appeared to do in the opening minutes with a sucker punch on Pascal Papé. He surely won't play in the quarters as a result.
Pens: Spedding 2, Parra
Tries: R Kearney, Murray
Pens: Sexton 2, Madigan 2
France: 15 Scott Spedding, 14 Noa Nakaitaci, 13 Mathieu Bastareaud, 12 Wesley Fofana, 11 Brice Dulin, 10 Frédéric Michalak, 9 Sébastien Tillous-Borde, 8 Louis Picamoles, 7 Damien Chouly, 6 Thierry Dusautoir (c), 5 Yoann Maestri, 4 Pascal Papé, 3 Rabah Slimani, 2 Guilhem Guirado, 1 Eddy Ben Arous
Replacements: 16 Benjamin Kayser, 17 Vincent Debaty, 18 Nicolas Mas, 19 Alexandre Flanquart, 20 Bernard le Roux, 21 Morgan Parra, 22 Rémi Talès, 23 Alexandre Dumoulin
Ireland: 15 Rob Kearney, 14 Tommy Bowe, 13 Keith Earls, 12 Robbie Henshaw, 11 Dave Kearney, 10 Jonathan Sexton, 9 Conor Murray, 8 Jamie Heaslip, 7 Sean O’Brien, 6 Peter O’Mahony, 5 Paul O’Connell (c), 4 Devin Toner, 3 Mike Ross, 2 Rory Best, 1 Cian Healy
Replacements: 16 Richardt Strauss, 17 Jack McGrath, 18 Nathan White, 19 Iain Henderson, 20 Chris Henry, 21 Eoin Reddan, 22 Ian Madigan, 23 Luke Fitzgerald
Venue: Millennium Stadium, Cardiff
Referee: Nigel Owens (Wales)
Assistant Referees: Wayne Barnes (England), Leighton Hodges (Wales)
TMO: Graham Hughes (England)