Manchester: One city, two clubs, and a match like no other

Tonight's showdown is all about which half you're in – blue or red

If you judged it only by the price of a ticket, tonight's Manchester derby is not just the only game in town; it is the biggest game of the year.

A ticket-exchange agency was last night offering two seats to watch Manchester City against Manchester United for £4,512.98, though it did promise "a clear view of the pitch".

In those terms, every other football match this year is a sideshow. A ticket for next Saturday's FA Cup final between Chelsea and Liverpool can be yours for £441. A ticket for Chelsea's Champions League final against Germany's Bayern Munich costs £878.

For those who support City, which, according to popular folklore, is most of Manchester, this is their day of reckoning. If they win tonight they will top the Premier League on goal difference. Should they win their two remaining fixtures, at Newcastle United and at home to Queens Park Rangers, they will be champions for the first time since 1968.

In the red half of Manchester, City supporters are known collectively as "bitters", their judgement eroded by the acid of years of envy. It reached its zenith in 1999 when the Daily Mirror printed a photograph of Manchester United playing Bayern Munich in the Champions League. Alongside was one of Manchester City losing at home to Mansfield Town in a competition called the Auto Windscreens Shield in front of a crowd of 3,007. At City's next home game, the Daily Mirror's man was told not to leave the safety of the press room for his own protection.

In the words of author Colin Shindler, whose book Manchester United Ruined My Life summed up the lot of a generation in blue: "Watching Manchester United lose is a pleasure that never palls."

Unlike Manchester United's fixtures against Leeds United and Liverpool, the game against City is not known for its off-field violence. But many police will be in riot gear and an alcohol-exclusion zone has been imposed from the city centre to the Etihad Stadium two miles away.

There were 34 arrests when the two sides met at Wembley in last year's FA Cup semi-final, won by a goal from City's Yaya Touré, brought in from Barcelona on a salary of £185,000 a week.

There were some City fans, including Shindler, who resented the takeover by a consortium from Abu Dhabi that transformed a club that was teetering towards insolvency into the wealthiest sporting institution in the world.

Until then, City's victories against United had been isolated triumphs in a guerrilla war. This season has been a contest of equals. In the long term a struggle between one side able to tap into unlimited oil revenue and one that owes £439m can end only one way, though that is to ignore the resilience of Sir Alex Ferguson, Manchester United's great helmsman.

This will be his 45th derby in a career in which he has encountered 14 different managers of Manchester City. This is, he said, the most critical of them all; a game that will decide the balance of power for this season and beyond.

In 1968, United responded to City's seizure of the title by winning the European Cup a few weeks later, casting a shadow that has only just begun to lift. This season, they did not even make the knockout phase of the tournament. No other prize is available.

Perhaps it is the red half of Manchester that is becoming bitter. A Manchester United-supporting businessman, Shaun O'Brien, who owns a vehicle-recovery business opposite the Etihad Stadium, attempted to block its expansion by parcelling out his land into square-foot plots and selling them to United fans at £250 a time. Last week, he was persuaded to sell up to City, though it is not known whether the deal included a ticket for tonight's game.