New Zealand rugby league centre Clinton Toopi will be sidelined for up to a year after suffering a serious knee injury while playing for English Super League club Leeds.

Toopi is ruled out of the World Cup starting in October and will miss the remaining two months of Leeds' challenge for the Super League title.

He damaged his anterior cruciate ligament during the Challenge Cup semi-final loss to St Helens over the weekend.

"He will be out for a long time, it will probably be around nine months and it could be a year," Leeds coach and former Kiwis mentor Brian McClennan told the Yorkshire Evening Post.

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

Toopi had already missed four months of the season with a dislocated shoulder.

He joins Brent Webb, Rob Burrow, Ali Lauitiiti, Jamie Jones-Buchanan, Ryan Bailey and Danny McGuire on a long Rhinos injury list.

"The knee gave way under me," said Toopi, who hobbled off five minutes before halftime.

"I just felt like there was no support."

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