The midfielder flicked home David Galbraith's cross in injury time to rescue a point and a 1-1 draw.
It was no less than the lads deserved after dominating the first half but coming in at half-time 1-0 down after Gary McSheffrey's early penalty.
The home side were on top after the break, chances were limited and the points looked to be staying in the Midlands before Marney's late intervention.
Boss Colin reflected: "The first half was quite pleasing. We were looking for a continuation of the weekend but we found ourselves chasing the game after a bit of rash challenge for the penalty, rash in the sense that there wasn't much danger, so it was a soft penalty to give away.
"We had plenty of shots, attempted crosses, corners and set-pieces, so the first half was alright.
"Second half was wasn't as good, not as fluent and they started to put pressure on. They had something to cling to. But getting the goal at the end was reward for the industry they put in.
"In the first half we played well, second half we didn't but the positive thing is we kept going."
Colin Calderwood saw Dean Marney's late equaliser just reward for his young side's refusal to give up in their FA Premier Reserve League opener at Coventry City last night.