West Ham owner David Gold revealed he was forced to watch the latter stages of his club's 2-2 draw with Leicester City from a room inside the King Power stadium.
The KP has become known for its feel-good atmosphere this season, but things turned sour when goals from Andy Carroll and Aaron Cresswell put the Hammers in front.
Leicester fans were in foul mood after referee Jonathan Moss sent off Jamie Vardy for diving and also gave West Ham a controversial penalty.
SIGN UP NOW
Want to become a GMS writer? Sign up now and submit a 250-word test article: http://gms.to/haveyoursay4
Gold and his co-owner David Sullivan were targeted with abuse while sitting with their families. Both opted to leave before full-time.
Gold explained: "We didn't stay to applaud our own players off as felt threatened. We've spoken to Leicester and they've told us they would look into it."
Taking to Twitter to vent his anger, he added: "I want Leicester to win the PL (Premier League) and I am pleased for their fans but behaviour towards us was unacceptable".
Leicester's home ground was a very different scene from the one that attracted headlines just weeks ago, when supporters were plied with free beer and doughnuts to celebrate the birthday of owner Vichai Srivaddhanaprabha.
The heated exchange also saw one fan complain that his 8-year-old nephew was hit by a plastic bottle thrown by home fans, while referee Moss had drinks chucked at him.
Leicester's lead at the top of the table now stands at just 5 points after the result saw them drop 2 points, and Spurs capitalised in emphatic style with a 4-0 victory at Stoke on Monday night.
Claudio Ranieri's side do not need added distraction, but the fallout from the West Ham game continues, with Vardy's one-game ban set to be extended after he was charged with improper conduct for swearing at Moss.
Now, Leicester could find themselves in hot water once again for their fans' behaviour.
Should Leicester be punished for their fans' actions against West Ham? Have your say in the comments!