Southend's Peter Gilbert and Liam Dickinson came back to haunt Plymouth, scoring goals in a 2-0 win to keep the crisis club rooted to the foot of the table.
Dickinson nearly signed for the Pilgrims in the summer before joining the Shrimpers, and put the hosts ahead on 64 minutes after Durrell Berry brought down Michael Timlin.
Dickinson slotted his penalty low into the bottom left-hand side of the goal, with goalkeeper Jake Cole going the right way.
The visitors were reduced to 10 men two minutes later when captain Carl Fletcher received a straight red for violent conduct after grabbing Timlin.
Dickinson was twice denied by Cole, the second a fine one-handed save that forced a Ryan Hall corner from the right, from which Gilbert grabbed his first goal for Southend from close range at the near post.
It was the first time he had scored in nearly eight years, the last one coming when he netted for Plymouth against Bristol City.
The second half followed a poor first half in which neither side recorded a shot on target.
Southend 2-0 Plymouth: Match Report - view commentary, squad, and statictics of the game as it happened.