Lamont was a key player for Scotland at the World Cup

After helping the Scots reach the World Cup quarter-finals, Lamont started his first Northampton Saints game of the season last Saturday.

And he suffered a serious injury to his right knee just 17 minutes into the match against the Pertemps Bees.

Named Scotland Player of the Season 2006-07, former Rotherham and Glasgow star Lamont has been capped 35 times.

A Northampton spokesman told BBC Sport: "Sean will need surgery but we have a first class medical team and hope to have him back in time for next pre-season."