Peterborough had defender Josh Knight sent off in a second-half flare-up during a goalless draw with Charlton.
Knight was dismissed by referee Andrew Kitchen in the 54th minute after kicking out at Charlton forward Jesurun Rak-Sakyi as the pair clashed on the floor.
Rak-Sakyi was hugely fortunate not to follow Knight down the tunnel, escaping with a yellow card for lashing out at Knight in retaliation.
Another Peterborough player, Jack Taylor, was also booked for an initial foul on Rak-Sakyi which sparked the incident.
Charlton were unable to make their numerical advantage count, with captain George Dobson firing over and substitute Corey Blackett-Taylor being denied by Posh goalkeeper Will Norris.
Ryan Inniss had earlier squandered Charlton's best chance of a low-key first half when heading over from a Sean Clare corner.
Peterborough rarely threatened, with League One's leading scorer Jonson Clarke-Harris coming closest when his header midway through the first half was kept out by a smart Ashley Maynard-Brewer save.
Taylor tested Maynard-Brewer in stoppage-time after dribbling from box to box only to be denied.
Charlton went up one place to 13th.