Star five-eighth Steve Larkham may struggle to be ready for the first Test of the year against England after MRI scans revealed he had a torn hamstring that would sideline him for four to six weeks.

Larkham sustained the injury during the Brumbies 37-14 loss to the Waratahs on Sunday night and will face an uphill battle to play in another Super 14 match this year.

More worryingly, if his period out of the game stretches to six weeks or beyond he would be pushing it to be match-ready for the Telstra Stadium Test against the defending World Cup champion on June 11.

The injury also comes at a crucial time for the fourth placed Brumbies, who face a tight run to the finals with matches against the Hurricanes, Reds, Highlanders and Crusaders.

Adding to the Brumbies woes ahead of this Saturday's vital clash with the third placed Hurricanes are doubts over the fitness of captain Stirling Mortlock and classy centre Matt Giteau.

Mortlock strained his left shoulder during a tackle against Waratahs winger Wendell Sailor, while Giteau is still troubled with a niggling knee injury he sustained during the Commonwealth Games sevens competition in Melbourne last month.

Larkham said he aimed to return for the final Super 14 round match against the Crusaders but felt it would probably take longer than that to recover.

"I missed most of the 2001-02 season ... with a hamstring injury, so I know how dangerous they can be in terms of trying to rush back too soon," he said.

"At this stage we are shooting for the last game of the round series, but in all honesty I wont be ready until the semi-finals."

Brumbies coach Laurie Fisher said he would now just have to wait for x-ray results on Mortlock.

"Stirling and Giteau are probably 50-50 to play at this stage, so were giving them until Thursday to prove their fitness," he said.

While Fisher acknowledged losing Larkham was a huge blow for the Brumbies, he said it would give Gene Fairbanks a chance to settle into the No.10 jersey.

"It's certainly a blow not having Bernie (Larkham) there and it's certainly going to change the way we'd like to play," Fisher said.

"(But) it will certainly be interesting to see how (Gene) goes over the next few weeks, to see if he does have a future at number ten (and) it will certainly give us an indicator for the years to come."

Fisher admitted without Larkham directing the attack, the Brumbies would play a less expansive game.

"We certainly won't be able to play with as much of the width as we can get out of Bernie," he said.

"Gene's go to is certainly much more (about) his footwork, his capacity is to be more direct to the line and to get runners a little closer off him."

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