By . Press Association Reporter . West Ham defender Joey O'Brien has withdrawn from the Republic of Ireland squad through injury. The 28-year-old, who met up with his international colleagues in Malahide on Sunday, is to return to his club for treatment on a knee injury. Out: West Ham defender Joey O'Brien (left) has withdrawn from the Ireland squad with a knee problem . Sitting them out: O'Brien will miss Ireland's games against Oman and Georgia this week . A Football Association of Ireland spokesman said: 'The Football Association of Ireland today confirmed that Joey O'Brien has withdrawn from the Irish squad, and will return to his club for treatment on an ongoing knee problem.' O'Brien's withdrawal means manager Martin O'Neill now has 26 players at his disposal as he prepares for Wednesday night's friendly against Oman in Dublin and the opening Euro 2016 qualifier in Georgia on Sunday.
Joey O'Brien has pulled out of the Ireland squad with a knee injury . West Ham defender has not been replaced by Martin O'Neill . Ireland take on Oman on Wednesday and Georgia on Sunday .