The England star will be replaced by James Haskell
The Lions have been handed a massive blow ahead of the tour of New Zealand with the news that England and Saracens number eight Billy Vunipola will not travel.
Vunipola, one of the world's leading number eights will miss the tour as he requires treatment on a shoulder injury. He will be replaced by fellow England international James Haskell.
"It is really disappointing for Billy and we know how much he was looking forward to joining the squad", head coach Warren Gatland said on Sunday evening. "He has been carrying an injury and feels he wouldn't be able to contribute fully to the Tour and needs further medical treatment."
"We really appreciate his honesty in making this decision and wish him luck with his recovery."
Vunipola was selected last month for his first Tour, and was set to travel alongside older brother Mako. The 24-year-old missed the majority of the Six Nations with a knee injury, but has impressed in recent weeks for Saracens. He was named man-of-the-match in the Champions Cup Final earlier this month.
Haskell's inclusion means he will travel on his first Lions tour. The Wasps star will join up with the squad next week after the Aviva Premiership Final next weekend.
Vunipola is the second player to pull out of the original squad since it was named last month. Scrum-half Ben Youngs withdrew a fortnight ago for family reasons.