Jennings hasn't trained or played since injuring his calf in the Origin opener in Melbourne and faces a race against time to be fit for next Wednesday's match.

A fitness test tomorrow will decide Jennings's fate with Bulldog Josh Morris tipped as the likely replacement, although it is understood performances at training this week will play a part in the selection.

The Blues' injury woes have forced them to call up Raiders pair Tom Learoyd-Lahrs and Monaghan as well as Morris as cover.

Both Monaghan and back-rower Learoyd-Lahrs joined the Blues in camp yesterday for a medical and light training run, before boarding the bus for the Central Coast.

If not required Monaghan and Learoyd-Lahrs will return to the NRL for the Raiders against the Manly Sea Eagles at Brookvale Oval on Sunday.

Six Blues players sat out the training run due to injury and Blues coach Craig Bellamy has given all his injured players a Friday deadline to prove their fitness.

Jennings and Tigers hooker Robbie Farah (rib cartilage) are the most serious concerns but several other players entered camp under injury clouds, including bench utility Craig Wing (hamstring), lock Paul Gallen (shoulder), captain Kurt Gidley (calves) and centre Jamie Lyon (ankle).

Comments from Blues coach Craig Bellamy in today's Canberra Times