Veteran forward Jamie Jones-Buchanan had a scan on Monday and is set to undergo surgery which will keep him out of action for six to eight weeks.
He revealed: “I have been struggling physically for a few weeks now.
“I did my knee against St Helens and I’ve just carried on with it. I’ve not been happy with some of the stuff I’ve been doing on the pitch; I’ve not been able to do my job as well as I’d like to so I need to get that looked at and addressed.”
The 36-year-old is one of three players definitely unavailable from the team beaten 38-10 by Castleford Tigers four days ago.
Prop Nathaniel Peteru is facing 10-12 weeks on the sidelines due to a ruptured biceps suffered just three games into his comeback from a similar injury to his other arm.
Captain/centre Kallum Watkins will miss the rest of the season with anterior cruciate knee ligament damage and Rhinos say stand-off Joel Moon, hooker Matt Parcell, second-rows Stevie Ward and Brett Delaney and full-back Jack Walker are all receiving treatment to knocks picked up against Tigers.
Scrum-half Richie Myler will see a specialist before being cleared to play after taking a bang to the head, but second-rower Carl Ablett (ankle) could be in contention following a one-game lay-off.
Centre Liam Sutcliffe and props Brad Singleton and Mitch Garbutt remain on the casualty list and front-rower Anthony Mullally will complete a two-match ban on Saturday.
Asked if Rhinos can cope with their mounting injury crisis, Jones-Buchanan insisted: “We’ll have to. Mikolaj [Oledzki] and young Cameron Smith have been outstanding when they’ve come in, they’ve looked really good and strong and Mikolaj got a deserved try last weekend.
“He gets better every week and the gaps in their game will be filled by gametime and experience. This is how you blood youngsters, but it is going to be a big challenge for us at Catalans and we are going to need to be at our best to get a result.”
He added: “It is very difficult there in the warm weather and Catalans are seeing some improvement.
“There’s a lot against us at the minute, but we can’t get too bogged down with that and be too disappointed. We have got to pick out the positives and go there with good strength of mind and put a good performance together.”
Even without a host of key players, Jones-Buchanan said Rhinos will be looking for a huge improvement on the performance they produced last weekend.
He described that as as “abysmal, upsetting, disappointing and embarrassing as well” and admitted: “We’ve lost a lot of times now at the Magic Weekend and it has become a bit of a hoodoo for us.
“It is a great fixture in the calendar and one we should look forward to, but for whatever reason we just aren’t performing well enough.
“I think we were all well off, myself included. This is one of the stages in the season when you need to gather your bags and start looking at where you can improve and quickly as well.
“There’s still a lot of positives and a lot of prizes to look forward to getting, but we need to quickly get back to playing well.”
Meanwhile, England Knights – whose performance squad includes Rhinos’ Walker and Sutcliffe, plus Greg Minikin and Jake Trueman of Castleford and Wakefield Trinity’s Reece Lyne – will play two games against Papua New Guinea this autumn, in Lae on October 27 and Port Moresby a week later.