A man dressed in a Manchester City kit tried to warm up with the team at a match.
He ran on to the pitch at Goodison Park in Liverpool as City's players warmed up for their champions' Premier League match against Everton.
Stewards noticed him and he was led away by security staff.
Merseyside Police said a 35-year-old man from London was arrested on suspicion of pitch encroachment and will be interviewed later.
A spokesman said: "Merseyside Police can confirm that a 35-year-old man from London was arrested before the Everton v Manchester City game this afternoon.
"The man was arrested on suspicion of pitch encroachment after he went on to the pitch. He has been taken to a police station where he will be interviewed."
Play was held up during the same fixture between the two sides last season, when a man ran on to the field and handcuffed himself to a goalpost.