Cheltenham moved into the League Two automatic promotion places thanks to a win over play-off chasing Southend.
Marlon Pack put the visitors ahead from the penalty spot after Alex Woodyard had brought down Russell Penn.
Paul Benson then doubled the Robins' lead with his first goal for the club when he capitalised on a mix-up between Michael Spillane and keeper Paul Smith.
Southend created little throughout, but got a late consolation through on-loan Ben Reeves's effort from 10 yards.
VIEW FROM THE DRESSING ROOM
Southend United manager Paul Sturrock told BBC Essex:
"I've got to put my hand up, I probably didn't pick the right team from the kick-off.
"Sometimes you make mistakes and you pay the penalty. In hindsight, there were one or two players I should have maybe started instead.
"We lost two ridiculous goals, the second goal was farcical, but we still had chances in the first half.
"The second half we totally dominated, there's several half-chances that we don't take."
Cheltenham Town manager Mark Yates told BBC Gloucestershire:
"We've now got to make sure we don't let ourselves down and put in a good performance on Saturday.
"We performed heroically, in terms of our effort. We didn't start the second half very well but we weathered it.
"The 93rd minute goal gave us a slight scare but I thought we thoroughly deserved the win."