The 28-year-old suffered the injury during his team’s Amlin Challenge Cup defeat in Toulon last Thursday and is expected to be out of action for nine months.

“Michael felt his knee give way in the game against Toulon and woke up with swelling the following morning,” director of rugby Brendan Venter told the club website.

“After seeing a specialist, scans picked up ligament damage and, had Michael continued to play on the knee, it could have caused long-term damage.

“So the decision has been taken to repair the ligament as, aged 28, Michael still has many years of rugby ahead of him.

“Michael is an important player for us and it is disappointing news.

“However, injuries do occur and it is one of the reasons why we believe in a rotation policy that sees us have a strong group available to play.”