Wales will be without Gethin Jenkins for the next five weeks with a knee injury, meaning the prop will miss part of the Six Nations Championship.
And both fly-half Rhys Priestland (knee) and Dan Lydiate (ankle) are likely to miss the opener against Ireland on Sunday, 5 February.
"Gethin is struggling and could be out for four to five weeks," said Wales coach Warren Gatland.
"Rhys will be struggling for the first game. We're assessing him day by day."
Lydiate, who was helped off the field playing for Newport Gwent Dragons last weekend, is struggling but there is more encouraging news on centre Jamie Roberts (knee).
"Dan Lydiate is touch and go. We're hoping Jamie Roberts will be OK," said Gatland.
Gatland admitted the loss of Jenkins and Priestland, who emerged as one of the stars of last year's World Cup, will be a major blow.
"Gethin is a huge loss for us for potentially the first two games of the tournament," he said.
"He's been playing exceptionally well for the Blues in the last month.
"He's a world class player. He's got a very good rugby brain and is able to asses things on the field. He's almost like a coach on the field.
"You get a lot of information from him at half-time, what's going right or wrong, tactically where we need to change.
"Rhys was probably the find, if not the best, fly-half at the World Cup. He really does fit the type of game we want to play.
"His kicking game and vision are excellent. He stretches opposition defences as well because he's not afraid to run.
"There's a very good balance to his game. You can't underestimate the space he created for our midfield at the World Cup.
"He was one of the reasons we saw some really big performances from Jamie Roberts, Jon Davies and Scott Williams. He will be a big loss for us.
"But there's experience to come in with James Hook and we may look at Gavin Henson in that position too."
Gatland revealed Leigh Halfpenny is likely to take over the kicking duties in Priestland's absence.
Jenkins limped off during the Blues' Heineken Cup win over Racing Metro on Saturday.
He has stayed behind in Wales to have treatment but was set to go to Poland by the end of the week.
Priestland and Lydiate were injured during their European matches, but both players will train in Poland.
Roberts is progressing well and will also continue his rehabilitation on Eastern European soil.
Clermont full-back Lee Byrne, who left the field with a thumb injury playing for Clermont Auvergne at the weekend, is able to take a full part in the camp.
Jenkins lasted just 32 minutes of the Blues' 36-30 win before being replaced and Baber revealed t the injury was a cause for concern.
Lydiate, who has been plagued by ankle trouble over recent months, was helped off the field as the Dragons beat Cavalieri Prato 45-16 in the Amlin Cup.