Leyton Orient and Northampton each finished with 10-men as a late penalty from Josh Wright sparked a mass brawl at the Breyer Group Stadium.
Wright’s spot kick cancelled out a first-half goal by Ryan Watson before ugly scenes marred the end of the match.
Scott Wharton was sent-off in the 88th minute together with Orient’s James Dayton by referee Alan Young for violent conduct after a brawl involving at least 14 players followed the penalty.
The Cobblers deservedly went in front in the 43rd minute when the unmarked Watson collected a headed pass by Vadaine Oliver and drilled home a 20-yard shot.
The visitors should have taken the lead after nine minutes when keeper Sam Sargeant sent an intended clearance to Matthew Warburton but his left-footed shot struck the woodwork.
Orient stepped up a gear after the interval and defender Dan Happe was denied an equaliser when Charlie Goode blocked a goal-bound effort before David Cornell palmed away a James Dayton shot.
The O’s were finally rewarded on 83 minutes when Wharton handled a cross in the penalty area and Wright stepped forward to convert the spot-.kick.
However before play could restart, tempers became frayed leading to the 14-man brawl.