Celtic manager Martin O'Neill remains in hospital after undergoing a "small procedure", the club have announced. O'Neill signed a one-year deal in June to become permanent manager after two interim spells last season culminated in a Scottish Premiership and Scottish Cup double. The Northern Irishman was in the dugout on Monday as Celtic started the new Premiership campaign with a 1-0 home win over Dundee. "In response to speculation, we can confirm that Martin O'Neill has undergone a small procedure in hospital," Celtic posted on social media. "We would envisage Martin being released from hospital in the next day or two and on behalf of Martin, we would like to thank supporters for their kind wishes.