They may have been largely written off at the most imposing Super 14 rugby venue, but that hasn't dimmed the noticeable confidence emanating from the Crusaders' camp.

The defending champions tackle the Bulls in semi-final two at a sold-out Loftus Versfeld in Pretoria on Saturday night (11pm AEST) as clear underdogs in their bid to make it an all-New Zealand final.

The facts are clear. The table-topping Bulls won all six home games this season, are unbeaten in their last nine there, have a baying full house behind them, a tough forward pack led by Victor Matfield, a gun goalkicker in Morne Steyn, and a matchwinner in Bryan Habana, whose try two minutes into injury time in the 2007 final secured the Bulls' first Super 14 title.

The Crusaders didn't arrive in Johannesburg until Monday, so have the travel and high altitude to overcome.

It appeared a simple equation but the visitors weren't buying into it.

Richie McCaw insisted the long journey and high altitude wouldn't be a factor, and felt their build-up could hardly have gone better.

That mood was further improved when All Blacks lock Brad Thorn (hamstring) was passed fit, while halfback Andy Ellis (ribs) was given until match day to prove his fitness amid an encouraging medical report.

McCaw rated Loftus one of his favourite venues. His Crusaders have a four-win, four-loss record there, including a staggering 54-19 victory in last year's round robin, and a more forgettable 27-12 defeat in the 2007 semi-finals.

"It's the same anywhere you go away from home. If you get into the game and on top early you take the crowd noise out of it a bit," he said.

"You can either feel lonely out there if you can't hear your mate yelling at you or you can just get excited. If you do well in those places it's the most satisfying. Saturday will be about making the most of the opportunity."

The Crusaders defied the odds this year, having lost their supercoach Robbie Deans and a host of frontliners, notably All Blacks stars Dan Carter and Ali Williams.

Under new coaching trio Todd Blackadder, Mark Hammett and Daryl Gibson, they won just one of their first five matches but fought their way back with trademark tough defence, and sealed fourth spot with a Leon MacDonald field goal to beat the Blues 15-13.

McCaw relished the chance to "slip under the radar" in recent weeks, knowing each of their final three matches were must-win.

Blackadder labelled the presence of New Zealand referee Bryce Lawrence a positive, and McCaw said discipline was their main buzzword against a side who will kick for territory and try to suffocate.

"Playing at altitude, anything inside your half, a penalty is pretty much three points. They've got a pretty good kicker in Steyn so that (discipline) is going to be absolutely critical," McCaw said.

The Bulls' only hiccup this week was in their midfield, with centre JP Nel suspended and in-form Springbok Wynand Olivier named to start despite a painful hip injury.

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