Twelve years ago, Manchester City triggered a seismic shift in English football by beating treble-chasing Manchester United at Wembley. Now City's own treble bid will come under threat from resurgent United in Saturday's FA Cup final.
With the Premier League wrapped up for a third successive season, City are two victories away from becoming only the second English club -- after United in 1999 -- to win the English title, the Champions League and the FA Cup in the same campaign.
City's current success and United's status as hopeful challengers would have been unimaginable when they last met in the FA Cup at Wembley in the 2011 semi-finals.
Just a few weeks after that showdown at the national stadium, United would clinch the Premier League title for the fourth time in five years, while also reaching the Champions League final.
In stark contrast to United's golden era under boss Alex Ferguson, City were still scarred by decades of disfunction and they headed to Wembley in the midst of a trophy drought that had become a source of embarrassment.
Such was United's superiority over their neighbours that fans cheekily displayed a banner in the Stretford End at Old Trafford which showed how many years it was since City last won a trophy.
To the intense frustration of the blue side of Manchester, the number on the banner was 35 by 2011.
Yet by the time they left Wembley on a grey April afternoon, City had delivered a statement of intent that would soon render that mocking banner redundant.
The first Manchester derby to be played at Wembley was an appropriate setting for a defining moment in English football.
Since City were taken over by Sheikh Mansour's Abu Dhabi-based group in 2008, their vast spending on new players had become the talk of the Premier League.
Ferguson had dismissively waved away talk of City posing a threat to United when he dubbed their rivals "noisy neighbours" in 2009.
But City were gradually improving under boss Roberto Mancini and the FA Cup semi-final served as their coming of age.
After United missed several chances, Yaya Toure, one of City's expensive recruits, scored the only goal of a fiercely-contested clash seven minutes after half-time.
The defeatism that had plagued City for so long was removed in one fell swoop.