Lions flanker Lewis Moody faces a race against time to be fit for first Test contention against New Zealand next week.
The Leicester forward has withdrawn from his place on the bench for Wednesday's clash against Wellington, when he will be replaced by his England colleague Richard Hill.
The Lions confirmed Moody had suffered an injury to his left knee in training, but the apparent seriousness was not revealed until coach Gareth Jenkins spoke to the media in Wellington on Tuesday.
Jenkins revealed that Moody is "out of the selection process" for next Saturday's game against Otago in Dunedin, and that will seriously hamper his Test prospects, given the Lions boss Sir Clive Woodward is likely to have finalised his first choice line-up by early next week.
Moody has not travelled to Wellington, remaining behind at the squad's Christchurch base for further tests.
Three players - Lawrence Dallaglio, Malcolm O'Kelly and Simon Taylor - have already been ruled out of the tour because of injuries.
The possible loss of Moody would be a huge blow, given his versatility at blindside and openside flanker, but it would appear the signs are not good.
Prop Andrew Sheridan, meanwhile, is battling to overcome an ankle injury sustained against the New Zealand Maori last Saturday, raising doubts about his prospects of being fit to face Otago. Like Moody, Sheridan is a serious candidate for the Lions' Test 22.
The British and Irish Lions team to play Wellington on Wednesday is:
J Lewsey (Wasps and England); J Robinson (Sale and England), B O'Driscoll (Leinster and Ireland, capt), G Henson (Ospreys and Wales), G Thomas (Toulouse and Wales); J Wilkinson (Newcastle and England), D Peel (Lanelli and Wales); G Jenkins (Cardiff and Wales), S Byrne (Leinster and Ireland), J White (Leicester and England), D Grewcock (Bath and England), B Kay (Leicester and England), S Easterby (Llanelli and Ireland), N Back (Leicester and England), M Corry (Leicester and England).
Replacements: G Bulloch (Leeds and Scotland), M Stevens (Bath and England), P O'Connell (Munster and Ireland), R Hill (Saracens and England), C Cusiter (Borders and Scotland), S Jones (Clermont Auvergne and Wales), S Horgan (Leinster and Ireland)
Gareth Evans was a first half replacement for the Cherry and Whites on Saturday afternoon, but the back rower's impressive carrying kept the hosts on the front foot when they needed it most to snatch a dramatic comeback win.
After his last ditch try clinched the 42-40 Aviva Premiership victory over Newcastle at Kingsholm on Saturday, Billy Burns told GRTV that all the Gloucester team deserve credit for hanging in there against a Falcons team who really made life tough for the Cherry and Whites.
Speaking ahead of Saturday's Aviva Premiership fixture at home to Newcastle Falcons (kick off 3pm), Director of Rugby David Humphreys emphasised the importance this weekend of Gloucester building on last week's impressive home victory against the Exeter Chiefs.
Speaking to the assembled national and local media, try-scorer Jonny May was delighted and relieved to have tasted victory on Saturday evening, and is looking forward to the European Rugby Challenge Cup final.
Tom Savage delivered a Man of the Match performance against Exeter Chiefs on his birthday on Saturday evening. He spoke to GRTV after the game about the importance of the European Rugby Challenge Cup win.
Speaking to the local media this week, John Afoa described the hard work that the Cherry and White have been putting in and that he is fighting fit ready for Saturday's European Rugby Challenge Cup semi final clash with Exeter Chiefs.
An independent disciplinary hearing today found that Mariano Galarza was selected for the Aviva Premiership match against Sale Sharks on March 29th, when he did not hold effective registration for Gloucester Rugby. The club was fined £5000 and received a two point deduction, suspended for two years.