Liverpool - Liverpool were forced to apologise after Manchester City's team bus was pelted by bottles and cans ahead of their highly-charged Champions League quarter-final on Wednesday.
Liverpool supporters surrounded the roads around Anfield and let off flares before throwing bottles at the City bus around an hour before kick-off.
The bus was reportedly rendered unusable by the damage and City sent for another for the post-match journey home.
Liverpool manager Jurgen Klopp apologised, saying: "Absolutely, I really don't understand it. We tried everything to prevent a situation like that. For Liverpool FC I have to say sorry."
Fans climbed up lamp-posts, walls and road signs to catch a glimpse of the teams as they arrived ahead of the hotly-anticipated first leg clash.
But the atmosphere turned sour when Premier League leaders City drove up to the stadium.
Liverpool swiftly issued a statement of their own pledging to identify the culprits.
"The club condemns in the strongest possible terms the scenes which preceded our Champions League quarter-final, which resulted in damage being inflicted on the Manchester City team bus during their arrival at Anfield," the statement read.
"We apologise unreservedly to Pep Guardiola, his players, staff and officials caught up in the incident.
"The behaviour of a number of individuals was completely unacceptable and the club will cooperate fully with the authorities to identify those responsible.
"The priority now is to establish the facts and offer Manchester City whatever support is necessary."
Although no-one was hurt in the incident, City manager Pep Guardiola admitted he was shocked by the scenes.
Showing his frustration, Guardiola referenced the attack on the Borussia Dortmund team bus, when a man let off explosives along the route to the stadium before their Champions League quarter-final against Monaco in Germany last year.
The attack left Dortmund's Marc Bartra with a fractured wrist and a police officer with hearing loss.
"We didn't expect that after what happened last season in Dortmund I didn't expect that," he said.
"I know that is not Liverpool, the history of the club is much bigger than this four or five or 10 guys. Hopefully it doesn't happen again."