London Wasps fly-half Ruaridh Jackson is expected to miss the remainder of the Aviva Premiership season, having suffered an ACL tear during his side's clash with Northampton Saints last weekend.
The 27-year-old underwent an MRI scan which revealed the full extent of the injury sustained in the Wasps' 20-16 victory at Adams Park, and he is now likely to miss between six and nine months.
"It's a real blow to lose him after he played so well in pre-season and against Northampton," said the club's director of rugby Dai Young. "Our medical team will be monitoring Ruaridh carefully and supporting him through this frustrating period."
Scotland international Jackson joined the Wasps from Glasgow Warriors earlier this year.