A Crystal Palace supporter has been arrested after he invaded the Selhurst Park pitch to confront Damien Delaney at half-time of their 4-0 home defeat by Sunderland.
The result - in a crucial fixture they needed to win against a relegation rival - has left them at significant risk of returning to the Championship and represented a new low in their season, while Sunderland's was revived.
Palace conceded three goals in the six minutes leading up to half-time, leading to widespread booing among their fans and chants of "you're not fit to wear the shirt".
It was as they were walking off at half-time that the fan broke onto the pitch to confront Republic of Ireland international Delaney, coming face-to-face with the defender and appearing to grab his shirt before being restrained by security.
Delaney was substituted and replaced by Andros Townsend before the second half, which Sam Allardyce said had nothing to do with the incident, while the fan was arrested by police at Selhurst Park.
Palace boss Allardyce was asked if that incident contributed to Delaney's substitution, and he said: "No. We played a very, very good game in that system with that team at Bournemouth (on Tuesday), and then completely lost the way we should have played in that system at home.
"I had to change the system to try and help the players get better."
Their defeat, after two goals from Jermain Defoe followed earlier finishes from Lamine Kone and Didier N'Dong, left Palace in 19th place with a points total of only 19 from 24 league games, the same as 20th-placed Sunderland.