Winger Ryan Hall will also miss the rest of this season and Rhinos could take on in-form Warrington Wolves on Saturday without six other first-choice stars.

Toopi injured a knee in the first half against St Helens – his third comeback game after four months out following knee and shoulder surgery – and Rhinos coach Brian McClennan said: "He got scanned yesterday and he's done his ACL (anterior cruciate ligament) and he needs to get other work done too.

"He will be out for a long time, it will probably be around nine months and it could be a year.

"He's had a hell of a season, but there's nothing we can do about it."

McClennan added: "Ryan Hall has broken a bone in a foot and got some joint damage and he's out for the season as well."

Of Leeds' other casualties from the cup battle, McClennan added: "Ali Lauitiiti has a hamstring strain and he will be struggling for this week now.

"Danny McGuire has shin contusions and we are assessing him. Hopefully he can be right to play this week, but we are going to have to make a decision later. That is a real 50-50 one at this stage.

"Rob Burrow will be having a cog (cognitive) sport test tomorrow to make sure he's okay after his bang to the head.

"He went back on, but we need to make sure he's right."

Brent Webb (back), Jamie Jones-Buchanan (hamstring) and Ryan Bailey (ankle) all missed the semi-final.

McClennan said: "Jamie will be out for four weeks. Bails (Bailey) has got severe bone bruising and he'll be out for two to four weeks.
"With Brent Webb, we are trying, but it is unlikely he will make it in time for this week."

Toopi, pictured, Lauitiiti and Jones-Buchanan have all been dogged by injury this year and McClennan admitted: "We haven't had them long, but that's footy, you move on.

"I have said from the word go that the 17 we put out on the field is our best 17. We will crack on with it."

The injury crisis is the last thing Rhinos needed following their cup exit.

"We have missed out on our goal of the Challenge Cup, but we can still grab this season back and get to Old Trafford and try and win the premiership," said McClennan.

"We have still got a bit of work to do, we've still got five games to go.

"We have got a really big test against Warrington this week because we are going to be digging deep into our squad."