West Brom say midfielder Jake Livermore moved to confront a West Ham fan after he made a comment about the death of his baby son,
England international Livermore, who was substituted just after the hour during Tuesday night's Premier League clash at the London Stadium, had to be escorted down the tunnel following the incident, which was not clearly picked up on CCTV footage.
West Ham acted quickly to eject the fan, who was spoken to by stadium staff on Tuesday evening, and are working with West Brom and the player himself to determine exactly what happened.