Davis is an invaluable member of the Blues side, having made 167 career appearances for the Club.BCFC
Davis suffered the injury during an afternoon training session at the Trillion Trophy Training Centre, Wast Hills.
The 27-year-old was booked in for an operation today and afterwards Tweeted that it had been a 'success' and he would be back 'stronger than ever'.
The Club will have a clearer picture of his required rehabilitation process in the next few days and will update in due course.
The misfortune is naturally a major blow for Davis, who was looking in excellent shape in pre-season, and Manager Garry Monk.
Davis has proven himself as an invaluable member of the side since joining from Wolverhampton Wanderers in August 2014.
Able to play in a variety of positions and consistently making an impact in the midfield fray with his energy, mobility and leadership, Davis made 38 appearances in the Championship last season.
Davis was named Players' Player and Supporters Player of the Season in 2016/17.