Rebels scrum-half Nic Stirzaker will miss Friday's clash with the Hurricanes in Melbourne due to an ankle injury.
Stirzaker injured his ankle during the latter stages of last weekend's defeat to the Sharks.
He initially sustained the injury during a pre-season clash with the Waratahs, and had displayed solid form in the Rebels' last few matches before experiencing this latest setback.
"It's disappointing for Nic, who has worked so hard to be fit enough to play a key role in our last few matches after missing a large chunk of the pre-season," Bryce Cavanagh, the Rebels' head of Athletic Performance, told the Melbourne-based franchise's official website.
"At this stage we are unsure of the full extent of the injury; Nic will see a specialist later this week and the picture will be a little clearer then.
"He won't play this week, but at this stage we're not sure how long he will be sidelined for."
Meanwhile, the Rebels may be able to call upon the services of prop Toby Smith, who missed the clash with the Sharks due to a shoulder injury.
Smith will undergo further testing throughout this week ahead of a return to full training and potential selection in the Rebels' side to host the Hurricanes.