Gloucester star Mike Tindall looks likely to miss England's tour of South Africa after suffering a suspected broken leg.
Tindall was carried off and taken straight to hospital following a collision with his England colleague Toby Flood during Gloucester's 19-12 Guinness Premiership defeat against Newcastle at Kingston Park.
The 28-year-old, who returned home last night with his leg in plaster, will undergo a scan on Sunday to confirm whether he has a fractured tibia.
If so, 53-times-capped Tindall faces a 12-week lay-off but, all being well, should recover in time for England's World Cup defence.
In the short term, he faces missing out on Gloucester's Premiership title bid and England's Test match appointments with the Springboks in Bloemfontein (May 26) and Pretoria (June 2).
Recalling the accidental clash, Flood said: "I stepped one way and I think Mike instinctively stepped the other, then I felt his shin hit my thigh really hard.
"It was just one of those things nobody can do anything about, but I feel desperately sorry for Mike because he is a nice bloke and a great player.
"It is deeply upsetting to see anybody seriously injured, and I just wish him all the best."
Tindall, a World Cup winner in 2003, started four RBS 6 Nations Championship games this season and is a key part of England head coach Brian Ashton's planning.
Injury-plagued Jonny Wilkinson also failed to last the distance, going off with a rib cartilage problem in the same game.
Flood added: "It is obviously disappointing to see Jonny go off in any game, but to be fair he just took a whack in the ribs and he was fine down in the changing room after the match.
"Obviously, he is a bit sore, but it doesn't seem too serious, thankfully."
Gloucester's losing bonus point returned them to the Premiership summit above Leicester, but attention tomorrow will be concentrated on relegation matters.
Northampton, European champions seven years ago, will drop into National League One if they lose against lunchtime opponents Wasps and do not collect a losing bonus point, then fellow relegation contenders Worcester beat London Irish later in the day.
If both Northampton and Worcester lose, or Saints beat Wasps in a dress rehearsal for Sunday week's Heineken Cup semi-final clash, then the relegation issue will not be decided until April 28 when Saints host Irish and Warriors entertain Saracens.
Wasps will not offer Northampton any favours, given their need for maximum points in the title play-off race.
Although Wasps rugby director Ian McGeechan has rested Lawrence Dallaglio, Tom Rees and Alex King, while Joe Worsley is on the bench, he still parades a powerful line-up that includes a return for England wing Paul Sackey after three months out injured and Danny Cipriani switching from full-back to fly-half.
McGeechan said: "We've rested Tom Rees, Lawrence Dallaglio and Alex King to give them longer to recover fully from the bumps and bruises they have picked up in two hard games we've had in the previous two weeks.
"In Alex's absence, Danny Cipriani starts at fly-half, which is a great opportunity for him to test himself and take his game forward, and he gives us some extra attacking options behind the scrum."
Bottom club Northampton, with only two away wins in the Premiership all season, have at least received a boost with the return of highly-rated centre Jon Clarke.
Clarke suffered a broken ankle just 30 minutes into Saints' opening league game of the campaign against Newcastle seven months ago, but a successful return during a midweek Guinness A League game meant head coach Paul Grayson had no qualms about handing the 23-year-old an immediate first team recall.
When Worcester run out against Irish at the Madejski Stadium, the result of Northampton's game against Wasps will be known.
Worcester rugby director John Brain said: "The players know that an opportunity could present itself possibly on Sunday afternoon, but we have got to be in the right frame of mind to take it.
"I am confident we can perform well, and if we do that we will be in with a real chance of winning the game.
"We have got to make sure we look after the ball and make sure we defend well against what can be a potent attacking team."
Elsewhere on Sunday, play-off hopefuls Saracens will look to pile the pressure on Wasps - they are currently two points above McGeechan's men - by defeating Vicarage Road opponents Harlequins.
