The Ibrox captain claims last Sunday's 1-0 defeat by Raith caused him greater personal pain than the day his club plunged into administration in February 2012 and admits shellshock has left him barely able to remember his actions after the final whistle at Easter Road.
He accepts greater flak than ever is now flying in the direction of McCoist ahead of United's visit and has called on everyone inside the dressing-room to ease the pressure weighing heavily on his shoulders by atoning for the latest in a series of disastrous cup displays. "The players obviously owe the manager this weekend for the support he has shown us - myself, in particular - over the past couple of years with administration," he said.
"It would be great to give him a bit back. After the support we took to Easter Road, it would be great to give the fans something to shout about in the wake of a tough week for them.
"We are going to need men, we are going to need leaders and what a chance we have for players to show those attributes. If you look at past Rangers teams who have been successful, it was a case of how they bounced back from a setback. That is the road we have to go down.
"I would imagine they [United] are the bookies' favourites, although, with the expectation that comes with this club,
we will be expected to progress.
"I think we will need a bit of luck. If we
put on a good performance and play to our capabilities, we will win the game."
McCulloch insists he has never felt more pained than at the instant referee Kevin Clancy blew for full-time against Raith last weekend and he includes the series of events that dragged the club towards liquidation under
the disgraced Craig Whyte regime in that.
"I would say hearing the full-time whistle was definitely the lowest point of my career and I'm factoring in everything," said the 35-year-old. "I'm only speaking on behalf of myself, but
it doesn't get much lower. I didn't know what
I was doing after the final whistle.
"My first thought was that I needed to show
a bit of respect to the team that had won, so
I shook their hands and then I think I tried to get back to the dressing room to get away from it all, but I was told I wasn't allowed.
"I sat somewhere, I can't remember where.
I went up for the medal and we just came in, but the dressing room, as you would expect wasn't the best place to be. The players have been speaking to each other to see how we can
move on. It is all about Saturday now."
McCulloch does not believe that the game being played at Ibrox will necessarily give his side an edge. "It is more familiar and it is our stadium, but Dundee United will bring a really good support, so I wouldn't say there will be an advantage," he remarked. "What we need is our leaders in the dressing-room to stand up, we need our young boys to go and embrace it and have a togetherness as a team. We need to keep it together and get over the line."