Liverpool will field different teams in two separate competitions within 24 hours after the EFL announced the date of their Carabao Cup quarter-final with Aston Villa will not be changed.
The Reds will play at Villa Park on 17 December at 19:45 GMT and will compete in the Club World Cup semi-final in Qatar the following day at 17:30 GMT.
Manager Jurgen Klopp had initially ruled out the prospect of playing both fixtures.
But the EFL said keeping the date followed a “request from the club”.
A Liverpool statement said: “We would like to thank the EFL for their efforts to accommodate us and we can confirm alternative dates were discussed, but ultimately none were considered suitable without compromising the scheduling of the competition itself or placing an undue strain on our playing staff.
“As a result, we will be utilising two playing squads simultaneously, with one squad participating in the Fifa Club World Cup in Qatar and another in the Carabao Cup.
“The club would like to take this opportunity to underline that while this is not an ideal scenario, it is an outcome which was arrived at with the best interests of the competition, our fellow clubs and ourselves as the sole motivating factor.”
On Tuesday Klopp said alternative fixture dates for the Villa tie were “just no good for us”.
“The final decision about the team line-ups has not been made,” he told BT Sport. “It’s not to be decided now. Now we have a little bit of time to think it through.”
Liverpool now have nine fixtures in December, with a run that includes a league match at home to Watford on 14 December, the EFL Cup tie with Villa three days later, a first Club World Cup game the following day and a final match in the competition on 21 December.
Klopp’s side then return to league action away at Leicester on 26 December.
In the aftermath of their last-16 EFL Cup penalty shootout win over Arsenal, Klopp said his side would not be “the victim of the problem” when discussing the fixture congestion.
In theory, the Reds would have faced a seven-hour flight of more 4,000 miles from Birmingham – after facing Villa – to Qatar, were they not fielding separate teams.
An EFL statement said Liverpool had committed to “fielding a team that is largely consistent with those that have participated in earlier rounds of this season’s competition” at Villa Park.
EFL football services director Dave Cookson said: “In these exceptional circumstances the decision was taken having received clear assurances from the club that there will be a level of consistency in team selection, a feature which is key to ensuring integrity is maintained.”
The EFL said maintaining the fixture date was “the best decision in minimising the impact of rescheduling the final stages of the competition”.
There are no midweek slots available in 2019 other than during international breaks and the first legs of the EFL Cup semi-finals are scheduled to be played in the week commencing 6 January.
Top European clubs have previously said they will boycott the Club World Cup from 2021 after Fifa approved the expansion of the tournament to 24 teams.
Two games in 24 hours – can Liverpool fans do both?
Liverpool fans who turn out at Villa Park have two flight options that would give them a chance of making kick-off in Qatar the next day.
A flight from Birmingham Airport at 07:50 GMT on 18 December lands in Doha at 17:30 local time, leaving three hours to get from the airport runway to the stands at Education City Stadium.
The cost of that flight was £614 one way at 22:00 GMT on 5 November. The journey from airport to stadium is around 30 minutes, so with a smooth progress through security, getting to both games looks possible.
There is also one leaving London Heathrow at 08:00 GMT on 18 December, landing 17:45 local time. That flight cost £509 at 22:00 on 5 November.
Other examples of when fixtures pile up…
In April, Venezuelan club Deportivo Lara played two matches in the space of six hours – one of which was in the Copa Libertadores – and they won both.
On the same day, another Venezuelan side, Zamora played two fixtures 4,000 miles apart, losing 4-0 at Deportivo La Guaira in the league and 3-2 at Brazilian side Atletico Mineiro in the Copa Libertadores.
Arsenal and Manchester United played on consecutive days in November 2001. The Gunners lost 4-2 to Charlton in the Premier League on 4 November and on the same day United were beaten 3-1 by Liverpool at Anfield, also in the league.
On the next day 5th November, Arsenal beat United 4-0 in the League Cup.
And in November 1987, striker Mark Hughes played for Wales and Bayern Munich in two countries on the same day.
After playing for his country, Hughes recalled: “There was a Lada to whisk us off after the match. I had to get changed into my kit on the plane.”