It has finally arrived. Manchester City host Manchester United in what is, with some merit, being billed as the biggest game since the Premier League's inception in 1992.
Sir Alex Ferguson's Reds, smarting from their 4-4 draw against Everton eight days ago, lie three points ahead of City at the top of the table, but a win for the Blues tonight will see them take first place thanks to their superior goal difference.
Roberto Mancini's side were eight points behind less than three weeks ago after the 1-0 loss to Arsenal on Easter Sunday. But three successive victories against West Brom, Norwich and Wolves have taken them to within three points of the Premier League summit.
United have taken just four points from a possible nine, losing to Wigan and beating Aston Villa before their eight-goal thriller against the Toffees.
And four is the operative number, with England's two best sides making it a quartet of derbies for the campaign.
For both City and United, the season started against one another on a capricious day (weather-wise) at Wembley in August.
CITY 2-3 UNITED, COMMUNITY SHIELD (AUGUST)
Two months later, drama was replaced with madness as City went one better than their 1989 forefathers to give their supporters The 6-1...
UNITED 1-6 CITY, PREMIER LEAGUE (OCTOBER)
Another competition, and another red card. Vincent Kompany was the controversial recipient as City fruitlessly rallied in the second-half to make it a close-run contest. Much to Ferguson's chagrin.
CITY 2-3 UNITED, FA CUP (JANUARY)
United and City through-the-years gallery: