Steve Jagielka will take all the plaudits for his sweetly-struck winner but team-mate, Phillip Edwards' injury-time intervention which deflected Jamie Slabber's goal-bound effort on to and then over the bar, was just as crucial in helping Stanley end Grays' 15-game unbeaten start.
The win was even more impressive when you consider that the visitors were reduced to 10 men with 24 minutes still to play when substitute and creator of Stanley's winner, Andrew Mangan, was sent off for two bookable offences in as many seconds.
The opener came when Gary Roberts produced a wonderful bit of skill that took out both Andy Sambrook and Jamie Stuart and Mullin slotted home from the resulting cross.
Grays were much better in the second half and were rewarded seven minutes in when Aaron McLean escaped down the right, skipped past Edwards and crossed for Michael Kightly who, after taking his time, crashed the ball into the top corner.
Stanley introduced Mangan to freshen up their forward line and the 19-year-old certainly left an imprint on the game - despite only being on the field for five minutes.
He set up Jagielka's volleyed winner by robbing Jamie Stuart and picking out the ex-Shrewsbury man at the back post two minutes after his introduction.
Mangan then plunged his side into crisis three minutes later by ridiculously getting himself sent off for first hacking at McLean and then, seconds after, kicking the ball away.
In the final 10 minutes John Nutter fired agonisingly wide for the hosts and then, with seconds left, Slabber found himself all alone in the box only for Edwards to make a stunning goal-line clearance.