Celtic are "miles off where they would expect to be", according to former Parkhead midfielder Scott Allan, who reckons the opening goal will be more vital than ever for their fragile confidence in Sunday's Old Firm derby. Speaking on the BBC's Scottish Football Podcast, he was surprised at the lack of response from Martin O'Neill's side after the weekend's 3-0 Premier Sports Cup defeat by Rangers at Ibrox as they lost 3-1 in their Europa League opener at home to Ferencvaros. "The season started off quite promisingly for Celtic, Europe aside, and then, after that kind of early promise, the balloon looks as though it's burst," Allan said.