The fire service was called out to Watford's home match against West Bromwich Albion after an advertising board started smoking.
Firefighters attended Vicarage Road and extinguished the fire before it could spread, reports BBC Sport.
The incident occurred moments before half time, with the match tied at 0-0, and caused minimal disruption to proceedings on the pitch.
The match has been touted as a must-win game for the Premier League's basement club West Brom, with reports suggesting that manager Alan Pardew could be dismissed if they lose.
The first half ended goalless.