Rhinos are facing their biggest challenge – McClennan

The Leeds coach is not overly concerned by his squad's injury problems or lack of form ahead of Sunday's Gillette World Club Challenge.

He insisted yesterday that their pursuit of a record-equalling third success will not be affected by either fitness doubts over Scott Donald and Brett Delaney or the fact they have lost two of their four Super League games so far this season.

But he accepted Melbourne are formidable opponents. They have dominated the NRL recently, reaching four Grand Finals, and in Greg Inglis, Billy Slater and Cameron Smith possess argubly the sport's three finest footballers.

"It is certainly the biggest challenge as a club we have had," said McClennan. "Melbourne are the best side the NRL have produced in quite a few decades and are a team that is evolving the game of rugby league very quickly.

"But we want to do Super League proud. We've a lot of experience in the big games and we'll give a good account of ourselves."

Leeds – who will share the 50,000 prize fund between their squad if they win – are preparing to compete without Donald, the Australian winger who scored their only try in the 11-4 triumph over Melbourne in the 2008 World Club Challenge.

"He's not progressing as well as we would have liked," said McClennan. "But if he's not right, we're very confident in the players we've got available in that position."

The Super League champions, who lost against Castleford and Wakefield before stuttering to victory over Salford on Friday, are hopeful centre Delaney will return to the side, freeing his deputy Kallum Watkins to switch to Donald's flank.

It would be the biggest match of 19-year-old Watkins's blossoming career.

"Kallum's a very exciting young talent – he's up there with Kyle Eastmond and Sam Tomkins in Super League," said McClennan.

Melbourne have won the title just once beating St Helens 44-0 in 2000.

Castleford Tigers have signed Wigan Warriors winger Shaun Ainscough on a month's loan. His signing will offset the loss of Richard Owen who is likely to be out for the season after breaking his leg in two places at Bradford last Friday

Wakefield Trinity Wildcats' wideman Damien Blanch is set to make his first Super League appearance in 10 months at St Helens tomorrow night.