When Manchester City won the Premier League with a century of points in 2018, the mantra outside the Etihad was that Pep Guardiola had to retain the title before his team could be considered great.
So they did. Edging out Liverpool in arguably the best title race in living memory with 98 points.
That same season they also become the first club to land a domestic treble.
Enough, you would think, to be thought of as being more than a bit special.
Now, it seems, the goalposts have moved.
City might be closing in on their third title in four seasons, with an extraordinary sequence of wins made even more astonishing by the fact that everyone said it couldn't be done in this Covid-affected season.
But it seems that unless they win the European Cup then the mantle of greatness will never be theirs.
Guardiola's side made it 21 victories in succession against Wolves on Tuesday night.
In terms of the major European leagues, Ajax hold the record with 26 consecutive wins – unless you count the 27 won by Welsh club The New Saints in 2016.
The previous best winning run in English football was provided jointly by Preston North End in 1892 and Arsenal in 1987. Both clubs won 14 consecutive games.
The mantle of European champions is indeed special. It means you can stick a star above the club crest of your shirt for a start.
And in terms of the global recognition that City's owners crave, it would be huge.
But the Champions League, once the group stages are out of the way, becomes a knock-out competition.
Should that really make it THE measure of greatness?
Liverpool won it in 2005 despite finishing fifth in the Premier League, just 37 points behind Chelsea.
Chelsea themselves became European champions at the end of a campaign when they finished sixth.
That isn't to denigrate those achievements.
Liverpool's win over AC Milan in 2005 was the most incredible game I have ever had the honour of reporting on. It really was the miracle of Istanbul.
Seven years later, Chelsea beat the odds to overcome Barcelona with 10 men in the semi-finals before defeating Bayern Munich on their own soil in the final after falling behind with just seven minutes remaining.
But great teams? Really?
Manchester United 1968, 1999 and 2008, Liverpool 1977, 1978, 1981, 1984 and 2019, Nottingham Forest 1979 and 1980, Aston Villa 1982 undoubtedly have their own valid claims on greatness.
But what about Arsenal's Invincibles? The Busby Babes and the Wolves team of the 1950s?
What about Bill Shankly's Liverpool or the team built by Kenny Dalglish that had Barnes and Beardsley running riot?
Howard Kendall's brilliant Everton side won two titles in three years in the 1980s and Jose Mourinho's Chelsea claimed back-to-back Premier Leagues.
The Manchester United team that lifted the first two Premier League titles was arguably better than the one that claimed immortality by winning the Treble.
Guardiola's is setting new standards – certainly in English football.
Every season he makes it his mission to win every trophy he competes for.
Yes, City have spent a fortune to make it happen.
But would Liverpool have won the Champions League and Premier League in successive seasons without signing the world's most expensive goalkeeper and centre-back?
Would the Class of '92 become legends without Roy Keane, Jaap Stam, Andy Cole and Dwight Yorke, all signed for fees that were huge at the time?
Greatness, like beauty, is in the eye of the beholder. And it comes in many forms.
