FC United are two wins away from a place in the third round of the FA Cup and a tie against the club they broke away from

It feels slightly outlandish, even bearing in mind everything we know about the FA Cup. Could it really be that FC United of Manchester are only two wins from a place in the third round and, whisper it, a possible date with Manchester United? The Red Devils against the Rebels. It is difficult to think there would ever be a tie laced with more intrigue, charm and fascination and maybe, from Sir Alex Ferguson, acrimony, too.

The king of the put-down has already pithily dismissed FCUM as "publicity seekers", so goodness knows what he will make of their first-round tie at Rochdale tonight being live on television. Ferguson has fallen out with the Manchester Evening News for giving 'Little United' what he perceives to be undue coverage. One reporter once asked for a comment about their success and a tribute for their driven, young manager, Karl Marginson. "Not interested! Not interested!" Ferguson thundered, and walked out of his press conference.

The bee in the Scot's bonnet can buzz out of control whenever FCUM are mentioned, which is strange because the people behind this breakaway movement still retain affection for the club they left behind. They just don't like the way the place is run and the way the supporters are treated. Their principles when it comes to the Glazer family and the rampant commercialism that drove FCUM's founders away from Old Trafford remain the same.

"Mind-blowing" is the word Marginson uses when he imagines the dream scenario of standing in the opposite dugout to Ferguson at Old Trafford. "But the away end would be empty. There's a saying among our fans: 'Not one penny more while Malcolm Glazer is at Old Trafford.' We'd turn up and play the match, but our fans wouldn't go. These people have principles. We'd play to the best of our ability, but we wouldn't sell any tickets."

There's a long way to go until then, of course, but they can be forgiven for allowing themselves to dream. This is the first time they have reached the first round and it represents possibly the biggest night in their five-year history. They will be backed by 3,200 of the fans who have abandoned United to follow this team of local lads across the villages and towns of northern England.

"We are United supporters, united as supporters," Alan Hargrave, a board member, says. "We try to follow the playing ethos of United. Some of us had 30 years following them home and away, going to places like Nou Camp. Now we're excited about going to Spotland [Rochdale's ground]. It's tremendous."

The aim, ultimately, is for Manchester to have three professional clubs. Marginson believes this is conceivable within the next five to 10 years. Plans have been submitted for a £3.5m stadium, so they can move away from playing at Bury's Gigg Lane (which costs £5,000 per game), with a decision on planning permission due on 25 November.

"We're no longer just a protest movement," Hargrave says. After three promotions, FCUM are now in the Evo-Stik League (formerly the Northern Premier), two divisions below the Football League. The general manager Andy Walsh remembers the club's first promotion from the North West Counties League Division Two: "We had an open-top bus ride, 200 yards to the nearest pub." Alan Gowling, a BBC Radio Manchester pundit, had said they would not last until Christmas, which has become the equivalent of Alan Hansen's 'you won't win anything with kids' moment. The club have printed T-shirts to that effect.

Marginson, 39, has been there since the start and now works for the club full-time, having given up his job as a fruit and veg delivery man. He first went to Old Trafford to see United play Everton in 1978. "Martin Buchan scored from 30 yards and I missed it because I'd left 10 minutes before the end and was at the bus stop." His last game was the 3-1 defeat to Chelsea in May 2005, shortly before the Glazers took over.

"Sir Alex Ferguson is the manager of Manchester United so he needs to look after their interests but, coming from Glasgow with his background in the shipyards and the trade unions, it's disappointing, and I would have done things very differently," he says.

"I would have walked away, personally. I'm not money-driven. I've got a car and a house, and it would be nice to earn a bit more, but if something like that happened [the Glazer takeover], I would have looked at the genuine fans – people I have grown up with – and I would have walked away. I would have said: 'Stuff it, I'm off.'"

The divisions FCUM have created are brilliantly encapsulated in Ken Loach's film Looking For Eric, when supporters of the two clubs become embroiled in a long and impassioned debate about the rights and wrongs.

"Sometimes, if you're in love with something, it's hard to see the bad side," Marginson says. "But football is about more than the 90 minutes. Football has a deeper responsibility to its communities and its fans and, excuse my French, but they're getting the piss taken out of them at Old Trafford."