Leinster and Ireland centre Robbie Henshaw will miss the start of the 2017-18 season with the chest injury he suffered on the British and Irish Lions tour.
Henshaw's tour was ended when he was hurt in the Lions' 31-31 draw with the Hurricanes and he has since undergone surgery that will keep him out for up to four months.
That means Henshaw will definitely miss the start of the Guinness Pro12 season and he faces a race to be fit for Leinster's European Champions Cup pool games in October and also Ireland's November internationals.
He returned home from the tour last week and had surgery in Dublin on Monday, after which Lions head of medicine Dr Eanna Falvey revealed the extent of the injury.
"That was a pretty significant injury, he's completely avulsed the muscle from the bone which requires to be re-attached to the bone," Dr Falvey said.
"That's usually about a 16-week recovery. He may do slightly better, but that's probably what we're looking at."