IF an outsider wants to understand the essence of the Manchester derby, Terry Phelan, the former Irish International who wore the Sky Blue jersey in United v City clashes of the early-to-mid 90s, is the man to call.
"For me, this is the biggest derby in the world.
"I don't care what anyone says. You've got the Milan derbies, the Liverpool derbies -- and I was involved in the Liverpool derby with Everton -- Wimbledon and Crystal Palace that was a big derby, but Manchester United v Manchester City is a classic.
"The atmosphere builds up for weeks and months before. It's all in the anticipation, and as it comes closer, you can see the determination in the eyes of the fans.
"You're walking around Manchester and you've got the Blue half and the Red half, and they don't talk to each other," said Phelan.
Surely he's exaggerating. Not so. Take the Phelan family of Manchester as an example.
Terry, as a young child, took the Road Less Travelled around Salford where he grew up, and adopted City as his team to follow.
Only problem was, the rest of his family were Reds. Passionate Reds.
So, what happened when Phelan, of whom the clan were justly proud for forging a career in English football's highest level, was a Manchester City player and derby day came around?
Oh, it was simple.Very simple. Terry, the Famous Son, became Terry The Untouchable, at least for one day.
"My family are big Manchester United fans and they used to give me hell. Even my mother used to give me hell.
"Your own mother giving you a bit of stick because when you're in the derby and you're playing for Manchester City -- 'you're going to get mashed today, son.' That's the kind of stuff she'd say to me.
"Or it might be: 'Don't come around today, I might put some laxatives in your food.'
Half joking, wholly serious.
"And I'd say: 'Come and watch the game.' But if it was at Maine Road they wouldn't come. Seriously, they wouldn't darken the door of Maine Road.
"Plenty of fun, plenty of banter and stick, but they take the derby so seriously and they're so passionate, those fans, on both sides," said Phelan.
Now 43 -- he will be 44 on March 16 -- and based in Dunedin, New Zealand, where he is Football Development Officer for NZ's Football South, Phelan is looking forward to the game with a sense of eagerness.
He may be retired from playing in an often ruthless and completely results-driven business, but the supporter in Terry Phelan still comes out for matches involving City and United.
"We're a day ahead of you, so it will be the early hours of Sunday when it's shown over here. I could record it, but I like to see the matches live.
"City are having success at the moment and that's good.
"I just really hope that they can nick the league on Manchester United which is going to be hard, but they're hot on United's heels.
"And if they can get into the Champions League which I think they should do anyway, that will be a bonus," he said.
There's no doubting Phelan's passion for City, even though he never did play on a winning derby team.
"I've never been on a winning side. Obviously, they've (United) always had the upper hand, but it's just been brilliant to have played in the Manchester derby," he said.
Indeed, to this day Phelan has a special Man City towel he uses for the gym.
But, for all that, he could have been a Manchester United player.
The opportunity arose at the end of his five years with Wimbledon, during which the Dons famously deprived a rampant Liverpool team of the League and Cup double in the 1987/88 season.
"Yes, I had the chance to go to Manchester United in 1992, but obviously they wouldn't pay the money, which was right, in my opinion.
"Wimbledon wanted two and a half million pounds, and that was a lot of money then.
"Personally, as I'd been bought for just under a hundred grand, I didn't think I was worth two and a half million.
"A million, or a million and a half, would have been my estimate. Even the likes of Barcelona were knocking on the door, but they didn't want to pay the money and neither did Alex Ferguson, which was right," he said.
As a professional, Phelan would have been delighted to join either United or Barcelona, but once they baulked at the asking price, in stepped Peter Reid with a cheque for £2.5m and Terry's boyhood dream had come true.
In fact, the fee equalled the British record at the time for a defender -- and that had been set a year earlier by Phelan's Wimbledon club mate Keith Curle, who also went to City.
"It's always a childhood dream, isn't it? To play for a club in your own town.
"Manchester City is a big club and has some of the best fans in the world.
"We weren't far off in the years I was there. We were rocking, and we had good players and it was a great time. People always say Man City was a wonderful team then. I enjoyed it, it was great.
"But managers change, and there's chopping and changing and you sat back and you went 'well maybe I would have been better off at another club where we could have had a bit of stability and at Man City we didn't have the stability that we should have had.
"Reid left after my first year and I'm like: 'I've just come to a club, a great manager and he's gone after a year.
"You start thinking then 'am I going to be there much longer, what if a new manager comes in and he wants his own players, is the team going to completely change again, and you've got to start from scratch.
"It was a bit unsettling towards the end, but Manchester City will always be in my heart," he said.
Phelan can only look at Manchester United and wonder what might have been if the managers at City hadn't suffered 'revolving door' syndrome.
"Money doesn't buy you everything. I think it's important to trust in a manager who can bring out the best in the players, who can wheel and deal, who can be sat in that chair not just for eight months or a year, but for 10 years and build from the grassroots right the way up.
"It's about stability, about building a unit and a club. Manchester United was built before Ferguson got there, but he's been there for nearly 25 years and look what they have achieved.
"City have chopped and changed so often. How long will Mancini be there for? And if he goes, they have to put more millions into it," he said.
TERRY PHELAN FACTFILE
Born: Manchester, March 16,1967
Height: 5 ft 6 ins
Clubs: Leeds United 1984-86; Swansea City 1986-87; Wimbledon 1987-92; Man City 1992-95; Chelsea 1995-97; Everton (included loan period at Crystal Palace) 1997-2000; Fulham 2000-01; Sheffield Utd (Aug-Dec) 2001; Charleston Battery (USA) 2002-2005; Player-coach at Otago United (NZ) 2005-2007; coach to Otago Utd Senior team 2007-2009.
Where is he now: Curently Football Development Manager for Football South in Dunedin NZ.
Honours: FA Cup 1988.
Ireland: 42 caps (1991-2000)