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The Leicester forward has withdrawn from his place on the bench for Wednesday's clash against Wellington, when he will be replaced by his England colleague Richard Hill.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)
Speaking to the media following the 31-33 West Country Challenge Cup defeat to Exeter Chiefs at the Memorial Stadium, Director of Rugby David Humphreys was full of praise for his side's battling qualities in a bruising encounter but concerned about the injuries picked up.
The West Country Challenge Cup fixture against the Exeter Chiefs at the Memorial Stadium in Bristol on Saturday (kick off 3pm) will be Gloucester's last chance to work on things like new combinations says Director of Rugby, David Humphreys.
Speaking after the 30-21 West Country Challenge Cup defeat at Bath, Director of Rugby David Humphreys spoke of the improvements his team are making as preseason progresses but acknowledges that there is still work to do ahead of the start of the Aviva Premiership.
Speaking to the local media ahead of Saturday's trip to Bath Rugby in the West Country Challenge Cup, front rower Nick Wood spoke of the hard work put in across the extended preseason and highlighted the competition for front row spots in the squad.
Gloucester have named a 30 man squad for the latest round of West Country Challenge Cup action against Bath on Saturday, with Director of Rugby David Humphreys stressing the need to keep an eye on player workload ahead of what will be a long, tough season.
Describing the 50-7 West Country Challenge Cup win over Bath on Sunday as a '...good hit out...', wing Charlie Sharples admitted that it had been a good opportunity to put into practice things that the squad have been trying out in training in recent weeks.
Speaking to the local media after the 50-7 victory over Bath Rugby on Sunday, David Humphreys was happy with his squad's effort, with the most important aspect being the game time earned by his players.
Gloucester make wholesale changes to the side that started at Exeter last Saturday as they prepare to take on Bath at the Memorial Stadium, Bristol on Sunday in the West Country Challenge Cup (kick off 3pm). The Director of Rugby told GRTV that the players are raring to go and that he's looking forward to seeing different combinations in action.