As the world's best players travel to Qatar for the World Cup starting on Sunday, the Premier League is preparing for a step into the unknown.
For the first time, the tournament is taking place in the middle of the domestic season, and for a period of time which will be defined by how well each national team performs in the Middle East, clubs such as Manchester United, Manchester City and Liverpool have waved goodbye to their superstars at a crucial point in the campaign.
Arsenal, chasing a first title since 2004, opened up a five-point gap at the top of the table with a 2-0 win over Wolverhampton Wanderers on the final Saturday before the break, and afterward manager Mikel Arteta admitted that, for the next six weeks, he will be relying on blind luck.
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"When a team is in that moment, you want to carry on playing, of course, but that's not possible," he said. "I would train tomorrow but unfortunately they're not here. I wish those going to the World Cup the best and they will look after themselves. I'll touch wood and hope for the best."
Arsenal's start to the season, winning 12 of their first 14 games, has given them a chance of ending a near 20-year wait to lift the Premier League trophy but, for now, their challenge is in the lap of the gods.
Erik ten Hag, hoping to lead Man United back into the Champions League in his first season in charge at Old Trafford, is in the same boat. United have a Carabao Cup tie against Burnley scheduled for Dec. 21, just three days after the World Cup final, and the Dutchman will have no idea which of his players might be available for selection until after the World Cup semifinals, scheduled for Dec. 13 and Dec. 14.
Sources have told ESPN that United are hopeful of giving each of their World Cup players at least seven days of rest after their international commitments are over, but there is an acceptance that it might not be possible. After facing Burnley, Man United's Premier League campaign restarts against Nottingham Forest at Old Trafford on Dec. 27, that game kicking off a run of three games in eight days.
Ten Hag and his staff, according to sources, are planning to lean on the players not travelling to Qatar -- the likes of David de Gea, Victor Lindelof, Scott McTominay and Jadon Sancho -- when they come to pick a team to face Burnley, but want a stronger squad available to play Forest.
It might mean some players pressed into action sooner than planned. Sources have told ESPN that United and other Premier League clubs have asked national teams for the training and recovery data for their players so they can be monitored while they're in Qatar.
United are most concerned about the players who are travelling to the World Cup but not expected to play large roles for their countries. Training every day will keep them relatively fit, but with very little time for friendlies or training matches outside official fixtures, they could return to the club having lost their match sharpness.
"We have a lot of players who are going to the World Cup and we are happy with that because it means we have top-class players," Ten Hag said. "Hopefully, most will also be on the pitch because it guarantees they keep fit. When they're not playing, I'll be a little concerned about them."
Once players return from Qatar, club staff have also been told to keep an eye on their mental, as well as physical, conditions -- particularly after disappointing tournament exits.
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As Man City manager Pep Guardiola put it: "It's the first time in our lives it'll happen [a midseason World Cup] so we don't know how the players will come back. If you have six players who are world champions they will be really positive. Others may be depressed."
Guardiola, in particular, needs as many players as possible to come back in good condition. Of his established senior stars, only Riyad Mahrez and Erling Haaland are not part of the World Cup, and Man City are due to face Liverpool in the Carabao Cup fourth round on Dec. 22. Haaland, so impressive in the first few months of the season, has been urged to use his time off wisely.
"He will be in Marbella, for sure, and Norway," said Guardiola. "How perfect he'll be in the second half of the season depends on how he behaves in Marbella. He will play golf, hopefully not eat and drink too much, and come back in great shape for the second half of the league."
Club managers such as Guardiola, Ten Hag and Arteta will watch the World Cup from afar but they still have a lot riding on what happens in Qatar. For more than a month, they will have little control over the players who will decide whether their teams are successful this season and for the coaches -- and indeed the club supporters back home -- there will be an anxious wait while the tournament plays out more than 4,000 miles away.
The World Cup, for the first time, is taking precedence over domestic leagues across Europe. Depending on what happens, it could end up playing a part in deciding them.