Manchester City manager Pep Guardiola is "curious" about teams that have won a treble as his side bid to claim an unprecedented quadruple.
Manchester United are the only English side to have won the Premier League, FA Cup and UEFA Champions League in the same season.
They achieved the feat under Sir Alex Ferguson in 1999, and Guardiola did the same in Spain with Barcelona 10 years later, when the Blaugrana won La Liga, the Copa del Rey and the Champions League.
In 2012-13, the season before Guardiola took over, Bayern Munich became Germany's first treble winners.
City are on track to better even those achievements this season. They have already won the Carabao Cup and face Brighton & Hove Albion in the FA Cup semi-finals on Saturday. Meanwhile, they are favourites to win the Premier League title and kick off their UEFA Champions League quarter-final tie against Tottenham Hotspur on Tuesday.
Guardiola has regularly rubbished any prospect of City winning it all this season, but he said ahead of the meeting with Brighton at Wembley Stadium he is intrigued by United and Bayern's achievements, per ESPN FC:
"I'm quite curious about the teams that achieved something good, for the reason why and what they have done. It's clear that winning the Treble is not easy. It happened in Germany, I went there the year after Jupp Heynckes got it. I like to know the way they did it. And every time, when I look at these kind of big, big issues, always it's tough.
"There are always moments where you will be lucky, and having personalities in the big moments can help the team to achieve. But I cannot compare us with what United have done. They have done what we haven't."
City have not looked like a side under pressure recently.
Since they surprisingly lost to Newcastle United back on January 29, they have won eight league games in a row and never looked like slipping up.
Their Premier League title rivals, Liverpool, have done impressively well to maintain pace with the Sky Blues, but they have benefitted from some late winners in nervy matches:
City look ominously good, though, and their game in hand over the Reds means they have the league title in their hands:
They also look unstoppable in the FA Cup, with Brighton likely to be brushed aside on Saturday before a final meeting with either Wolverhampton Wanderers or Watford.
That leaves the Champions League as the final obstacle, the tournament City are least likely to win this season.
Spurs will be tough in the quarter-finals, and Cristiano Ronaldo's Juventus likely await in the semi-final before a potential final against Barcelona or Liverpool:
Given the mental and physical strain that will be put on Guardiola's squad as they go for the league and FA Cup, the Champions League may just be a step too far.
Juve and Barca have already all but wrapped up their respective league titles, so they can plan with the Champions League in mind. That is not a luxury afforded to Guardiola.