Leinster and Ireland flanker Sean O'Brien is facing up to six months out of action.

The Carlow man will undergo shoulder reconstruction surgery in the UK tomorrow.

It had been thought that the 26-year-old would return far sooner than that six month timescale, but a complication from previous shoulder surgery means he will face a longer period on the sidelines.

O'Brien missed much of last season with injury, including Ireland's victorious Six Nations campaign.