Rebels hooker Jordan Uelese will miss the rest of the season, with scans confirming the club's fears that he ruptured his ACL.
Uelese was ruled out of the Wallabies' June Series on Sunday, with suspicions he had suffered the serious injury, and scans on Monday confirmed the worst-case scenario.
The 21-year-old was on the field for just 10 minutes in the Rebels' win over the Blues in Auckland before falling awkwardly in a tackle on Blues no. 8 Akira Ioane.
Uelese will go under the knife on Thursday, and begin the long rehabilitation process.
Rebels general manager - professional rugby - Nick Ryan, said the news was a blow to the team.
“The news of Jordan’s injury is incredibly disappointing for everyone involved in Australian and Victorian rugby, the Rebels, but foremost for Jordan,” Ryan said.
“Jordan is a respected member of the Melbourne Rebels playing group, and someone who has showed great resilience and dedication to his rehabilitation to return from a shoulder injury this season.
“His resilience will be tested yet again, but we are confident that Jordan will apply himself to the process to get himself back to playing, meanwhile supporting his teammates as we look to chase our bit of history this Super Rugby season.
"The Club has great faith in quality players such as Anaru Rangi and Nathan Charles to lead the way for the rest of our campaign."
Rangi is a chance to be called up to the Wallabies' June squad, after Uelese's withdrawal, with his official replacement to be named on Wednesday.
NSW's Tolu Latu has been training with the squad, but there is no guarantee he will step into the main group.