Leeds Carnegie will have only one fit senior hooker available for their LV= Cup clash with Sale on Sunday after Andy Titterell was ruled out for five months.
The 29-year-old former England international, a Lions tourist to New Zealand in 2005, suffered a knee injury in training last week and scans have revealed he requires an operation on his anterior cruciate ligament.
The Yorkshire club are also without Steve Thompson, who is currently away with England, leaving Phil Nilsen as the only remaining first-team hooker.
Director of Rugby Andy Key said, "We are bitterly disappointed for Andy, however he will have the operation very soon and I am sure, given his nature and athletic strength, that he will be battling to be back as soon as possible.
"Whilst we have suffered a number of injuries this season, this is only the second time that a serious injury has occurred in training, with Dan White breaking his leg earlier this year which makes it even more frustrating for Andy.
"Unfortunately in the short term, with Steve Thompson away with England, that only leaves us with Phil Nilsen to cover at hooker. We have two very talented young hookers in Harry Hannan and Scott Freer but both are coming back from long term injuries.
"In the case of Scott, hopefully he will get some rugby under his belt in the next week and I am sure he will be pushing for inclusion in the first-team squad in due course.
"We have to make sure that we do not rush into a decision in case there are other options out there."