Bath Rugby made the announcement after a visit to a specialist revealed that the American international will require surgery on his troublesome shoulder.
In an injury similar to that of club mate Iain Balshaw, Lyle sustained a grade three separation of his A/C joint during the Zurich Premiership match against Bristol Shoguns in November. Despite making a brief comeback as a second-half replacement against Montauban three weeks ago.
Lyle felt that his shoulder was not 100% right in the contact situation, and a decision had to be made as to the best way forward for the back row player."After seeing a shoulder specialist, it has been decided that Dan will need surgery. It is likely that he will be out for the next twelve weeks," said Bath co-coach Mike Foley.