Star Western Force back James O'Connor has been ruled out of Friday's crunch Super 14 clash with the Hurricanes in Perth after succumbing to a hamstring injury.

O'Connor, who was named to play at inside centre, suffered the injury in the latter stages of last week's 39-7 demolition of Queensland Reds.

It was initially hoped the 18-year-old would recover in time to take on the Hurricanes but coaching staff made the call on Thursday not to risk the teenage prodigy.

Junior Pelesasa has been promoted off the bench to fill the void left by O'Connor, while Josh Tatupu has been called into the squad as cover.

Pelesasa, who has started just three games this season, faces the daunting task of trying to nullify rampaging All Black Ma'a Nonu, who holds a 7kg weight advantage in the battle of the inside centres.

"He's basically the spearhead for the Hurricanes," Force skipper Nathan Sharpe said of the 104kg Nonu.

"He's one of their key players so he's a guy we need to keep under control."

Defensive lapses and handling errors cost the Hurricanes dearly in their 33-17 loss to the Sharks last week but Force coach John Mitchell warned his charges to be on high-alert against the free-wheeling New Zealanders.

"They're a very attack-focused football team and they have the ability to open you up like a can of worms," Mitchell said.

"They've got threats all over the park.

"Nonu's just one of them. You've got (Alby) Mathewson, (Rodney) So'oialo, Andrew Hore, you've got a test front row.

"They've got threats all over the park and we are going to have to be at our very best come Friday night."

Sharpe said the Force, who enter the round six points adrift of fourth spot, needed to display a strong defensive resolve in order to hold out the Hurricanes.

"They are one of the teams that attack very well regardless of where they are on the field," he said.

"We've spoken about their ability to counterattack from broken play, from set play, and we've just got to be on our game on defence because they are a team that can cut anyone to pieces.

"It's a very important game for us ... every week is vital in our quest to get into the finals.

"The guys certainly enjoyed the win (over the Reds last week) but we shelved that pretty quickly.

"This is not a competition where you can rely on one week's performance to carry you through to the next.

"Certainly we learnt that lesson against the Brumbies (when they lost the next week against the Chiefs) and we don't want to repeat that against the Hurricanes."

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