Farrell has been beset by injuries since switching to union

Former England centre Andy Farrell has been ruled out of Saracens' first five Guinness Premiership games after suffering a thumb injury in pre-season.

The 33-year-old has struggled with a string of fitness problems since his switch from rugby league in 2005.

His latest setback resulted in him fracturing and dislocating a thumb when making a tackle against Western Force.

"It's totally frustrating - but you won't find me sitting in the corner and sulking," said Farrell.

The injury occurred only minutes after Farrell had arrived on the field as a second-half substitute in the friendly against the Australian side and led to him being replaced by his 17-year-old son Owen.

Saracens' medical team expect him to be out of action for eight weeks, ruling him out of Premiership games against Harlequins, Sale, Newcastle, Northampton and Bristol.

"It's especially frustrating after flogging yourself for eight weeks in pre-season and then just when you start to look forward to the games, this happens," added Farrell, who missed the final two months of last season because of a shoulder injury.

He revealed: "Things were going really well. I played out in Bayonne in a friendly the week before, felt in great shape and was looking forward to getting on the field against Western Force.

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"I can still train and I shall use this time to get fitter and stronger and turn this time into an advantage."

Farrell has been named as co-captain of Saracens, alongside new signing Steve Borthwick, for the forthcoming season.

"I will be arranging my training around the first team to make sure I am at all the sessions," he said.

"I'll be doing whatever I can to continue to help push the team in the right direction, maintaining the progress we have shown in pre-season."

Farrell missed the whole of his first season in union with toe and back injuries, while rib, shoulder and calf problems have also hindered his progress.