Six Nations 2018: Ireland's Sean O'Brien an injury doubt

O'Brien started Ireland's Test matches against South Africa and Argentina in November

Ireland flanker Sean O'Brien has emerged as an injury concern ahead of the start of the 2018 Six Nations.

Leinster have confirmed the flanker has had surgery on a hip injury, which has kept him out since last month's Champions Cup win over Exeter Chiefs.

O'Brien, 30, is now hoping to recover in time for Ireland's Six Nations opener against France on 3 February.

In a statement, Leinster say the target is to have O'Brien available 'during the Six Nations window'."

The British and Irish Lions star, who has played just four games for Leinster this season, missed the province's recent Pro14 derby wins over Munster, Connacht and Ulster after limping off during the victory against the Chiefs at the Aviva Stadium on 16 December.

"Sean O'Brien saw a specialist this week for the tightness in his hip as it hadn't responded to treatment as we would have liked," Leinster revealed.

"As a result he had a small procedure and the target is to have O'Brien back available during the Six Nations window."

O'Brien is the latest Leinster player to suffer an injury before the start of this year's Six Nations after centre Garry Ringrose sustained an ankle injury in the win over Ulster at the RDS.

The province has also revealed that Adam Byrne is to have surgery on a knee injury that he suffered on Ireland duty in November.

The winger's injury has not responded favourably to rehab and his recovery timeline will become clearer following the operation..