Star Carlton recruit Mitch McGovern has suffered a pre-season setback, the former Crow sustaining a back fracture in a training drill.
McGovern clashed heavily with a teammate and in a marking contest and crashed to the turf during an open training session at Ikon Park on Thursday.
The Blues reported the 23-year-old has "a small, non-displaced fracture of the back" after he was sent for scans on Friday.
"Often with this type of injury players can miss one to two games during the season, while for others it's not uncommon to not miss any at all," Carlton football chief Brad Lloyd said.
"Mitch will obviously continue to be monitored during this next period, however we're confident he'll be back training with the rest of the team following the Christmas break".
Carlton's players will complete individual programs away from the club during a mandatory three-week Christmas leave period negotiated by the AFLPA.
McGovern's switch from Adelaide to the Blues was one of the headline moves of October's AFL trade period.
The Crows received a first-round pick and SANFL prospect Shane McAdam from the Blues in return for the disgruntled forward, who demanded a trade with two years left on his contract.