West Ham have played down a half-time brawl between their fans and supporters of Major League Soccer side Columbus Crew in Ohio on Sunday.
Club officials dismissed the scuffle which marred the 3-1 victory as an "isolated incident".
According to local newspaper reports, punches were thrown when some Hammers fans approached rival supporters.
"We understand this was an isolated incident," said West Ham chief executive Scott Duxbury.
"It led to one initial arrest that was quickly dealt with by security staff.
"While we take such matters seriously and utterly condemn the actions of those involved, we must not let this mar what has been a positive trip so far and the excellent way we and our supporters have been treated in Columbus.
"The match was a fitting warm-up for the MLS All-Star Game which we are proud to be involved in."
Columbus police and Ohio state patrol were called to the stadium and the state patrol arrested one West Ham fan after the game for a minor disorderly charge.
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