Ireland forward Sean O'Brien is set to have hip surgery in the "next few weeks" that will rule him out of the World Cup in Japan, his club Leinster confirmed Sunday.
O'Brien, 32, missed Leinster's PRO14 final victory over Glasgow Saturday but he was given the honour of lifting the trophy after the match.
"Unfortunately [Leo] Cullen has confirmed that back row Seán O'Brien -- who lifted the PRO14 trophy yesterday in Celtic Park on behalf of the 57 Leinster players that had competed over the 23 game domestic season -- will undergo surgery in the next few weeks for a hip injury and as a result will be ruled out of action for up to six months," said a club statement.
"As a result he has been ruled out of the Rugby World Cup in Japan."
O'Brien has won 56 international caps for Ireland and started all three Tests for the British & Irish Lions on the tour to New Zealand in 2017.
The back row forward played his final match for Leinster in the Champions Cup defeat to Saracens and will end his 11-year spell at the club to join newly-promoted London Irish in the English Premiership next season.