Barcelona fans insulted and spat at Chelsea manager Jose Mourinho when he and his players arrived in Spain on Sunday for their Champions League clash.
The Premier League club said about 50 Barcelona fans were waiting for Chelsea at the city airport and some spat at the bus when Mourinho and the team were on board waiting to leave.
Former Barcelona assistant coach Mourinho had earphones on and ignored the abuse but then a series of spits were aimed at his window, Chelsea said on their official website.
They quoted Chelsea TV cameraman Kieren Startup, who was filming the scene, as saying: "There were very few police to marshal it, and they didn't seem interested once the players got on the coach to stop any abuse.
"It was intimidating, there was a lot of aggressive chanting at Mourinho to begin with, but he ignored it and then they moved on to angry gestures and spitting. Everyone else on the coach seemed to be unbothered."
Barcelona are 2-1 up going into Tuesday's second leg of the first knockout round tie at the Nou Camp after winning the first leg at Stamford Bridge on February 22.
Chelsea were a man short for more than 50 minutes after their Spanish left back Asier del Horno was sent off for a foul on Barcelona teenager Lionel Messi.
Mourinho accused Messi of theatrics, claiming his reaction helped get Del Horno dismissed.