Andy Murray admitted he would struggle to play the five matches in a row that Great Britain will require to lift the Davis Cup trophy.
Britain begin their campaign on Wednesday morning in Madrid with a gentle-looking opener against the Netherlands before their second group match against Kazakhstan on Thursday.
They are the clear favourites to progress to the quarter-finals, which are being played on Friday, with the semi-finals and final over the weekend at the Caja Magica.
Murray came through an equally hectic schedule in Antwerp last month to win his first singles title since hip surgery but has had time away from the court since to rest a slight elbow injury and welcome his third child, son Teddy.
The Scot said: "Playing five days in a row is going to be tough just now. I did it in Antwerp and I got through that tournament quite well at the end. But it was tough.
"And since then I've had a bit of a break as well, where I didn't train and practise as much. So five matches in five days would be difficult for sure.
"But that's one of the nice things about this event, and especially the team we have got just now, is that everyone can step in."
If captain Leon Smith does decide to rest Murray then Wednesday would surely be the day given the relative weakness of the Dutch singles players.
At a press conference notable mostly for the British players shoehorning lyrics from the film Frozen into their answers, Smith kept his cards close to his chest about who he will select.
He said: "I have a pretty good idea but we've kept it as normal and I'm going to speak to the guys tonight, so they can sleep on it and then we go."
Dan Evans is the highest-ranked player in the team with Kyle Edmund also above Murray, and both should be more than capable of guiding Britain to victory.
They are also competing with each other for the number one spot when Murray does play.
Evans said: "It will be a proud moment whoever goes out there and plays number one. Obviously Andy is a very good number two to have playing before us. And we have both had a good week's practice."
Despite his schedule concerns, Murray gave a positive update about his fitness, including on shifting the excess weight caused by a few too many biscuits.
"I've lost a little bit of weight," he said with a smile. "Not as much as I would like. But obviously getting to practise here and hopefully getting to play a few matches can also help with the last couple of kilos. Physically, my elbow's been really good so that's been positive."
Britain's Davis Cup success in 2015 was built on Murray's prowess in singles and doubles.
Doubling up under the new format would mean playing two matches in a day, which Murray admitted would be tricky.
The Scot said: "I guess we'll see what happens when we're out there. But, if that's what Leon wanted ultimately, then I'd do it."
The Netherlands were beaten 2-1 by Kazakhstan on Tuesday, making Wednesday's clash a must-win if they are to reach the last eight.
Dutch number one Robin Haase, who won his singles against Alexander Bublik before losing the deciding doubles alongside Jean-Julien Rojer, said: "Ranking wise, and of course with Andy being back, they're the favourites in our group.
"It's not over yet, in Davis Cup you never know, but it's going to be very difficult for us to go to the next stage."
Informed that Murray may not play, captain Paul Haarhuis said: "It doesn't matter. If they rest him they must be thinking he's not good enough, because why would you rest him? He was dying to play tennis I think."