Liverpool are genuinely nearing the quadruple.

Having defeated Villarreal 2-0 in the first leg of their Champions League semi-final on Wednesday night, the Reds are potentially only 180 minutes away from lifting their seventh European crown.

Marry that to having already won the Carabao Cup, sitting just one point off the Premier League summit and preparing for the FA Cup final to see exactly why history is genuinely being touted.

Liverpool chasing the quadruple

Now, of course, beating either Real Madrid or Manchester City as well as Chelsea in major finals won't be easy, never mind relying on dropped points in the league, but the quadruple has certainly never been closer.

All those times that supporters have gotten overexcited about City winning the Carabao Cup early in the year have never gone this far in terms of genuinely entertaining a quartet of trophies.

And really, that shouldn't be any sort of shock at all because the simple fact of the matter is that an English club has never won the League Cup, FA Cup, Premier League and Champions League in a single season.

Yes, that does also apply to when it was the old First Division and European Cup, too.

Liverpool 2-0 Villarreal Match Reaction (Football Terrace)

Which clubs have won a quadruple?

In fact, even when you look across European football as a whole, there are very few examples of 'quadruples' that hold up to the scrutiny that Liverpool's would be able to survive.

Besides, instances like the 'sextuple' that Barcelona won under Pep Guardiola can ultimately be chalked off on the basis that the six trophies were secured across a calendar year and not a season.

If we're talking about a strict criteria of the league title, European title and biggest two club competitions, then you're pretty much only left with 2012/13 Bayern Munich and 1966/67 Celtic.

The Bavarians won the Champions League, Bundesliga, DFB-Pokal and DFL-Supercup, while Celtic took home the Scottish Division One title, European Cup, Scottish Cup and Scottish League Cup.

Football - Bayern Munich v Borussia Dortmund - 2013 UEFA Champions League Final - Wembley Stadium, London, England - 25/5/13

Bayern Munich's Philipp Lahm (C) celebrates with team mates as he lifts the trophy after winning the UEFA Champions League Final

Mandatory Credit: Action Images / John Sibley

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Which clubs have won a treble?

As such, let's pause for a second and cut the European giants of old some slack by rewinding and looking at the clubs that Liverpool would join in the fabled treble rankings.

Besides, it seems pretty clear that the Reds would be in uncharted territory with their quadruple, but there are actually seven European clubs who can boast about winning the 'true treble' before.

No, we're not talking about Manchester City winning the League Cup, FA Cup and Premier League in 2018/19, but the exact, perfect triumvirate achieved by Manchester United 20 years beforehand.

That's the top-flight crown, first-most European title and the most important cup title of all with Goal having calculated the elite cohort of clubs and seasons that Liverpool would blow out of the water.

So, without further ado, be sure to check out the only seven European clubs to have won the treble in a stunning list that really puts what Liverpool are chasing into some perspective:

1. Celtic (1966/67)

Scottish League, Scottish Cup and European Cup

30th May 1967: Billy McNeill of Celtic receives the European Cup trophy from the President of Portugal after the Scottish side's 2-1 victory over Inter Milan in Lisbon in the European Cup final. Tommy Gemmell and Stevie Chalmers scored for Celtic which ensured a surprise 2-1 victory for the Scottish team. Celtic became the first British side to win the trophy and remain the only Scottish side to reach the final. (Photo by Central Press/Getty Images)

2. Ajax (1971/72)

Eredivisie, KNVB Cup and European Cup

3. PSV Eindhoven (1987/88)

Eredivisie, KNVB Cup and European Cup

STUTTGART, GERMANY - MAY 25: PSV Eindhoven goalkeeper Hans van Breukelen celebrates after PSV had won the 1988 European Cup after a penalty shootout at Neckarstadion on 25th May, 1988 in Stuttgart, Germany. (Photo by Simon Bruty/Allsport/Getty Images/Hulton Archive)

4. Manchester United (1998/99)

Premier League, FA Cup and Champions League

5. Barcelona (2008/09 and 2014/15)

La Liga, Copa del Rey and Champions League

Football - FC Barcelona v Juventus - UEFA Champions League Final - Olympiastadion, Berlin, Germany - 6/6/15

Barcelona's Lionel Messi celebrates with the trophy after winning the UEFA Champions League Final

Reuters / Kai Pfaffenbach

6. Inter Milan (2009/10)

Serie A, Coppa Italia and Champions League

7. Bayern Munich (2012/13 and 2019/20)

Bundesliga, DFB-Pokal and Champions League

Soccer Football - Champions League - Final - Bayern Munich v Paris St Germain - Estadio da Luz, Lisbon, Portugal - August 23, 2020 Bayern Munich's Manuel Neuer and teammates celebrate winning the Champions League with the trophy, as play resumes behind closed doors following the outbreak of the coronavirus disease (COVID-19) Manu Fernandez/Pool via REUTERS

Liverpool set to blow them out of the water?

All those incredible sides and Liverpool are on course to best them. Madness.

Now, ok, the huge elephant in the room is that the Reds still have to jump through some pretty tricky hoops to make it all happen and the one part of the quadruple that they've secured is technically the easiest.

With the League Cup already glimmering in their trophy cabinet, it means that they simply can't win the treble without securing the quadruple too because, well, that's the way the English season works.

Soccer Football - Carabao Cup Final - Chelsea v Liverpool - Wembley Stadium, London, Britain - February 27, 2022 Liverpool's Jordan Henderson and Caoimhin Kelleher celebrate with the trophy after winning the Carabao Cup Action Images via Reuters/John Sibley

So, in many ways, all these 'cup finals' that Liverpool have to come through will have an 'all or nothing' feel to them because just one defeat will be all it takes for the treble and quadruple to come crashing down.

And that's why so few teams have even knocked on the door of those feats, leading to the tiny list that you've read above, so don't underestimate for one second the madness that Liverpool are accomplishing.