Northampton flanker Tom Wood has lost his race to be fit in time for Saturday's Heineken Cup final against Leinster in Cardiff.
The Premiership player of the year had been sleeping in an oxygen tent in the hope of speeding up his recovery from a hairline leg fracture.
But Saints rugby director Jim Mallinder said: "It's actually one week too soon.
"He was very, very close. If we were desperate we could have taken a chance but it's not worth it."
Wood suffered the injury playing for his club against Gloucester last month and the news is a setback for Northampton as they attempt to win their second Heineken Cup.
The 24-year-old came to prominence on the international stage this year, playing on the blind-side flank for England and helping his country claim the Six Nations title.
But despite Wood's injury update, Mallinder remained philosophical ahead of the final at the Millennium Stadium.
"We have got a strong squad and we are playing well," added Mallinder. "It's a big blow but when you get to this stage of the season with only one player out, then you'd probably take it."
Meanwhile, Mallinder assured Saints fans there are no worries over Chris Ashton after the England winger revealed on Tuesday that he will be having an exploratory knee operation next week.
"Chris is fine. He took a heavy blow. He wasn't concussed or knocked out and carried on playing," said Mallinder.
"It's been out in the press about his knee injury and that's been ongoing for a couple of months. That's not an issue.
"He will be full on for Saturday. He's sat out contact training - he'd already got a split above one eye before that incident.
"The doctor was busy at half time, he was busy stitching up both eyes, but Chris is fine."
Northampton's Heineken Cup final opponents Leinster have a few injury problems of their own with talismanic centre Brian O'Driscoll suffering a knee injury in the Magners League play-off semi-final victory over Ulster on Friday.
Hooker Richardt Strauss (hip), scrum-half Isaac Boss (hamstring) and prop Mike Ross (leg) also picked up knocks.
Mallinder is working on the basis they will all be available, and insists his own side will be physically fresh despite the brutal nature of their Premiership semi-final defeat at Leicester.
"I think we are in good shape," he added. "Without doubt it was a physically intense battle last weekend and I thought our defensive performance was outstanding.
"We have got a fit squad; they are used to playing every week and watching then in training the last couple of days, you wouldn't think it was the end of the season, or that they were tired. We are not staggering to the line at all.
"If we had qualified for the Premiership final [a week on Saturday, 28 May], then we would have had things in our mind. But now we have only got one thing in our minds, and that is Saturday at 5 o'clock."