Neil Lennon has to rally his troops for a “miracle” trip to Turin following Celtic's 3-0 Champions League defeat by Juventus at Parkhead last night.
Goals from Alessandro Matri, Claudio Marchisio and Mirko Vucinic in the first leg of their last-16 tie all but ended the Hoops' European hopes.
The Celtic boss, surveying the damage and what lies ahead in the return game in fortnight's time, said: "We need a miracle. We have to try to be competitive and try to work our way into the tie but last night was the harsh reality of football at this level.
"We didn't get off to a good start but our reaction was fantastic.
"For 70 or 80 minutes we played fantastic football and were on the front foot.
"We needed a goal and Efe Ambrose had a great chance and that would have galvanised us.
"But the second goal burst the bubble and if you make defensive mistakes at this level you get punished and that's what happened."
Lennon blasted Spanish referee Alberto Undiano Mallenco and his officials for their reluctance to punish the Juventus players for what at times resembled a wrestling match in the visitors' box.
The Northern Irishman said: "I would like to ask the Italian journalists what they made of the way Juventus marked our players.
"It looked to me as if they were fouling at every opportunity.
"The referee was warned by our players to keep an eye on it but he ignored our requests time and again.
"Are the rules different in Spain and Italy to what they are in Britain? On that showing they must be.
"We played Juventus in 2001 here and Montero was marking Chris Sutton and the referee warned him but he persisted with it and he gave a penalty and we went on to win 4-3, so what is the difference?
"It is not rugby they are playing it is soccer. There is a way to defend and we do it as fairly as possible."
Juventus manager Antonio Conte, who stayed away from any controversy when told about Lennon's assessment of the referee, was satisfied with his side's performance during what was at times a frantic match.
He said: "Celtic are a good team but we knew this, and there was a fantastic crowd who were like two extra men and that can only drive a team on.
"So it was a difficult match for us, but we kept our heads.
"Celtic played with great intensity but we showed great maturity and overall it was an excellent result for us."