Jonny Wilkinson is battling to play again before Christmas after being cut down by another cruel injury blow.
The Newcastle fly-half looks certain to miss England's entire autumn Test programme, which features Twickenham clashes with the Pacific Islanders, Australia, South Africa and New Zealand.
Wilkinson's place in the 32-man elite England squad is set to be filled by Danny Cipriani.
Neither Newcastle nor the Rugby Football Union are speculating on how long Wilkinson will be sidelined after he dislocated his left knee during Falcons' Guinness Premiership defeat against Gloucester last night.
But it is understood a three-month absence is probable as he braces himself for detailed specialist advice following a scan today.
Newcastle rugby director Steve Bates said: "It is obviously disappointing for Jonny to receive an injury just when he was back playing fantastic rugby.
"But he has enormous strength of character, and I am sure he will come back stronger despite this blow."
In a statement, the RFU added: "The England coaching and medical teams are in close contact with Newcastle Falcons regarding Jonny Wilkinson.
"A further comment will be made after they receive the results of the specialist's review of his injured left knee."
It was initially feared that Wilkinson had suffered knee ligament damage when he limped off after being caught in a ruck during the game at Kingsholm.
Wilkinson was featuring in just his fourth match after undergoing summer shoulder surgery that sidelined him for England's two-Test New Zealand tour.
He has been plagued by injury since landing the winning drop-goal in the 2003 World Cup final against Australia.
He needed treatment on a shoulder injury after that match and has since picked up knee, bicep and groin injuries. He has also required surgery to cure kidney and appendix problems.
While Wilkinson ponders another lay-off, England manager Martin Johnson can only keep his fingers crossed that 20-year-old Wasps ace Cipriani enjoys an injury-free run.
Cipriani finished last season's RBS 6 Nations Championship as the player in possession of England's number 10 shirt.
He produced a commanding performance, kicking 18 points during a comprehensive victory over Ireland, but then an horrific ankle injury suffered while on Premiership play-off duty for his club against Bath ended Cipriani's campaign.
It was initially thought he would be out for six months, therefore being unavailable to contest an autumn Test place.
But Cipriani recovered six weeks ahead of schedule and was due to begin his comeback - against Bath - in the Premiership tonight.
Johnson can draft replacements into the elite squad at any time in the event of injuries.
Cipriani was originally named in the second-tier England Saxons squad while he continued his recovery throughout the summer, but with Wilkinson likely to be missing next month, promotion looks inevitable.
Johnson has other fly-half options within the main England group, including Gloucester's Olly Barkley, Leicester number 10 Toby Flood and London Irish's Shane Geraghty, but no-one fits the bill quite like Cipriani.
The RBS 6 Nations Championship 2015 was not poised to go down as one of the more "vintage" Championships, though there was great anticipation as the action headed into its final day. What transpired was something that nobody could foresee: "The Greatest Day in Rugby's Greatest Championship."