Full back Cullen - who scored a national record 48 tries in 58 Tests for New Zealand - helped Wellington Lions to reach the NPC final last month but now has to put his Munster debut on hold in a major setback to the 2002 Celtic League champions.
Christian will have a minor shoulder operation on Wednesday, said Munster coach Alan Gaffney. At the moment we cannot set a time on his likely recovery. We are hoping it won't be too long, but we accept that it could take him out of the early rounds of the Heineken Cup.
The delay to Cullen's appearance in Munster colours is a hammer blow to Jim Williams' team, coming on top of an already lengthy injury list that includes long-term victim World Cup flanker Alan Quinlan, who will be sidelined until March, Denis Leamy and Mike Prendergast, who are also out for the longer rather than short term.
In the immediate future they take on Cardiff Blues at Musgrave Park on Friday night in a Celtic League clash that Gaffney calls a critical match for two teams desperate to climb out of the bottom half of the table.
We are looking forward to the match, though yesterday (Monday) was the first time we will have had any sort of proper preparation with our World Cup players, he said.
A couple of them came in last week but today will be the first occasion this season that we have been together as a squad.
The most important thing at this stage is to work out where we are heading and getting ourselves organised.
Cardiff Blues team manager Derwyn Jones confirmed all five of our World Cup players are back training with us today. It is great to have Martyn Williams, Iestyn Harris, Rhys Williams, Tom Shanklin and Heino Senekal back - they are raring to go.
FRIDAY 28 NOVEMBER7.05, Celtic Warriors v Edinburgh, Brewery Field (Donal Courtney) BBC W7.30, Glasgow v Llanelli Scarlets, Hughenden (Alan Lewis)
SATURDAY 29 NOVEMBER5.30, N-S Ospreys v Leinster Lions, The Gnoll (David Changleng). S4C.