Skipper Keven Mealamu says the Blues will be out to produce a huge Super Rugby performance for teammate Kurtis Haiu against the Highlanders in Dunedin on Friday night.

Haiu, 26, faces a battle against cancer after scans last week found a tumour in one of his ribs.

The lock will need further tests, including surgery, to confirm the type of tumour and will be away from rugby indefinitely.

Mealamu said the news, which was made public on Wednesday, came as a shock to the players when they were told after their win over the Melbourne Rebels last Friday night.

"It's tough because I don't know if we'll get to see him again this year or if we'll get to see him in any team again," he said.

"Most definitely we'll be playing our hearts out for him this weekend."

The Blues go into the match at Carisbrook top of the New Zealand conference, thanks in no small part to the Highlanders' 26-18 upset over previous leaders the Crusaders last weekend.

The Auckland-based franchise are unbeaten in their past seven matches but they know they face a tough examination of their credentials by opponents who have noticeably stiffened in resolve with the arrival of new coach Jamie Joseph.

"It will be a big battle up front," Mealamu said.

"Both teams rely on their forwards to do well in order to play the style they want.

"I can tell you now, it's going to be a classic match where it's won and lost in the forwards."

Mealamu will be without fellow All Black frontrower Tony Woodcock at his side, the prop sidelined with an ankle injury.

He said replacement Tevita Mailau had shown his ability to step up with his performance against the Waratahs a fortnight ago when Woodcock was out with the calf strain.

Coach Pat Lam has made one other change, with Luke McAlister back at inside centre for fellow All Black Benson Stanley.

Among the five changes to the Highlanders' starting 15 is the return of All Blacks Jimmy Cowan and Adam Thomsonto halfback and blindside flanker.

Mealamu admitted that he had been surprised at how well the Highlanders had gone so far this year.

The southerners haven't finished in the top half of the table since making the semi-finals nine years ago, but seven wins from nine matches has them sitting in a wildcard spot.

"I think everyone is surprised," Mealamu said.

"They're playing like a well-drilled team - a team that really believes in what they're doing.

"Jamie has been a big influence down there -- a good Otago man -- and he's pulled it back to what they're really good at. They're back to the Highlanders of old."

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