Assistant manager Neil Baker planted the seeds for the play, where Byron Moore's low delivery was dummied by defender Harry Davis for skipper Luke Murphy to stoke into the top corner from 18 yards, having watched the Shrimpers concede space on the edge of their area against Fleetwood over Easter.
After discussing the tactic with boss Steve Davis, practice runs of the set-piece did not run smoothly.
"We did it on Saturday afternoon, we both chip in and Steve will say, `Have you got any ideas'," Baker explained. "I watched them play and Fleetwood scored from a little one to the near post.
"We saw that they were short on the edge of the box and we wanted to exploit that, which we did.
"He (Murphy) probably didn't get it on target in practice or hit a defender. He certainly didn't put it where it went. I think Harry tripped over it."
And Murphy confirmed that the old adage of mistakes in the dress rehearsal being no bad thing proved to be correct.
"We were doing a few in training on Saturday and thought, `The first one, we'll try it - if it's not on, it's not on'.
"They did leave a massive gap, we tried it and luckily for me it came off.
"It didn't come off yesterday (Saturday) so we'll just forget about that one and concentrate on today! He (Harry Davis) did trip over the ball, twice, so I think they were going to knock it on the head."