Ryan Cresswell grabbed a last minute winner for Rotherham over Cheltenham.
The Millers, who announced the appointment of Steve Evans as their new manager earlier on Monday, missed a first-half penalty when Jack Butland saved Lewis Grabban's effort.
Kaid Mohamed and Josh Low both went close as the visitors improved after a poor first-half showing.
Cresswell rose highest to head home Ben Pringle's corner to hand the hosts victory at the death.
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Rotherham United caretaker manager Darren Patterson told BBC Radio Sheffield:
"I thought we dominated possession, they showed what a good side they are in the second half.
"I'm proud of the way the lads have performed and the staff have stuck together.
"I bumped into the new manager at the hotel (this morning) and wished him and his assistant every success and hope that he's a success for Rotherham United."
Cheltenham Town manager Mark Yates told BBC Gloucestershire:
"It's disappointing with 30 seconds to go in added time to lose it but they probably got what they deserved.
"I thought they were good in the first half, but in the second half we were more like ourselves.
"But we go again. I'm not too angry, we're all disappointed but we've got four games left and it makes those games even more important.
"I don't have any doubt we can hold our nerves, we're disappointed to get beaten today but there's 12 points to play for and we're in the box seat."