Northampton Saints fly-half Piers Francis will miss the start of the Premiership season due to a jaw injury.

The 27-year-old sustained the injury during the pre-season friendly with Glasgow Warriors on August 19 as Saints claimed a 19-14 victory up in Stirling.

Northampton are set to kick off their domestic campaign on September 2 against European champions Saracens at Twickenham.

Francis, who only joined Saints from New Zealand outfit Counties Manukau this year, was recently called into the England fold for the tour of Argentina.

Saints have not put a date on when they expect Francis to return and he will have to compete with the likes of Harry Mallinder and Stephen Myler when he returns to full fitness.