An angry Millwall supporter ripped an assistant referee's flag from its pole following a goal-kick decision in the 3-1 home defeat by Leicester.
Angry with Alan Young's decision not to award a corner at The Den, the fan grabbed the flag, leaving it on the ground and Young needing a replacement.
BBC Final Score reporter Andrew James said it looked like "a broken umbrella".
The fan was led away by stewards following the incident.
Millwall have yet to reveal whether they will take any action against the supporter.
Leicester won the game against the managerless Lions to remain top of the Championship table.
Steve Lomas was sacked following Millwall's
Boxing Day defeat by Watford.