Fighting between at least 30 West Ham supporters and some 100 fans of Columbus Crew had to broken up by police and security staff during the match in Columbus on Sunday.
The trouble started after a handful of the Premier League club's supporters went into the north-east corner of the stadium where the US Major League Soccer team's most boisterous fans were based.
Rival groups began chanting at each other and fist fights broke out until police and security staff using mace and pepper spray eventually moved in to separate the sides.
Several people were handcuffed during the fighting but there was only one arrest - outside the stadium - for disorderly conduct.
US sporting rivalries are generally handled peacefully, although Columbus Crew supporters have a relatively rowdy reputation.
But their track record is nothing compared to that of West Ham fans, whose notorious hooligan element, the Inter City Firm, once enjoyed one of the worst reputations in English football.
This was dramatised in Green Street Hooligans, a 2005 film in which Elijah Wood played a US student who got involved in a hooligan group affiliated to West Ham.