More than 100,000 fans will be in attendance as the four most successful teams in the history of the Scottish League Cup meet in the semi-finals on Sunday.

Hearts face holders Celtic at Murrayfield (13:30), with Aberdeen v Rangers (16:30) to follow at Hampden Park.

Often considered the lesser component of the domestic treble, the spotlight has been on the competition since the last-four draw in September - and not just because of the mouth-watering fixtures.

Madness, then Murrayfield

So how did Murrayfield, the home of Scottish rugby, end up staging a national semi-final for the first time?

With Celtic and Rangers both playing in the Europa League on Thursday, having one game on Saturday, and one on Sunday as planned was not an option. But a contractual obligation to play the games at Hampden then became a problem. And a congested fixture list ruled out playing at the national stadium on successive weekends.

But there was much tumult when the Scottish Professional Football League proudly announced an unprecedented plan to stage both games at Hampden on the same day: one at 12:00 GMT and the other at 19:45.

"We are pleased to have come to an arrangement that suits everyone," a statement read.

It soon became apparent that that wasn't the case. Far from it. Hearts said they were "astonished". Aberdeen were "appalled".

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Hearts manager Craig Levein ladled on the outrage a few days later, calling it the "craziest thing", "beyond belief" and "madness".

A wave of incredulity and ridicule eventually led to a new plan, with Hampden Park Ltd waiving their right to stage both matches and the SPFL coming to a deal with Scottish Rugby to use Murrayfield.

Everyone happy? Not really. Celtic thought a ballot was the best way to decide which game moved to Edinburgh, describing the process as "irrational and discriminatory".

Celtic boss Brendan Rodgers said the new venue was "certainly not neutral" since Hearts had played league games there last season, but has since mellowed, calling Murrayfield a "beautiful, iconic stadium".

Then the tiff over tickets...

All settled? No chance. As soon as the fixtures were rearranged, the focus switched to ticket allocation.

Hearts and Aberdeen both demanded an equal split of the 67,000-capacity Murrayfield and Hampden, which holds 52,000, respectively. Sales at Tynecastle were brisk but the story was different at Pittodrie.

The Dons eventually received 20,300 tickets after denouncing their original share of 16,800. However, they have had to hand many back and have shifted fewer than 12,000 tickets.

"No harm done," was Aberdeen manager Derek McInnes' assessment. "Even for Sir Alex Ferguson's teams in the '80s it was quite consistent - 10,000 in Glasgow."

Ultimately, both games look like being sold out, with the Murrayfield tie boasting the biggest attendance at a Scottish football match in almost 30 years.

But what about the football?

All that carry-on overshadowed what promise to be two terrific contests between four of Scotland's biggest clubs.

Between them, the quartet have won the competition on 54 of the 72 occasions that it has been held since it began in 1946-47.

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Rangers - headed up since May 2018 by former Liverpool and England captain Steven Gerrard - lead the way with 27 tournament wins, with Celtic on 17, Aberdeen have lifted the trophy on six occasions, and Hearts have done it four times.

Celtic are going for three in a row, which would be a seventh trophy out of seven under the command of Rodgers, with Rangers the last team to celebrate three successive successes in the competition back in 1989.

Perhaps surprisingly, this is the first time since 1976 that these four clubs have reached the last four, when manager Ally MacLeod led the Dons to glory against Celtic in the final after thumping Rangers.