Raheem Sterling has cast doubt over the Premier League's plan to resume matches next month with many top stars still not back in training.
Sterling has insisted players would require at least a month of full training before they can be pitched back into big-match action - effectively ruling out the hoped-for return date of June 12.
Speaking in an interview with USA women captain Megan Rapinoe on his Youtube channel, Sterling said: "You can't come back in with one and a half or two weeks (of training).
"You'd need a full four to five weeks, especially if you're going to go back into competition, when you're literally paid to win. You do need to do that preparation - you can't just go straight in."
Sterling admitted to feeling "lost" when the lockdown was first introduced in March.
"The beginning (of lockdown) was definitely weird then I started to say to myself I can't keep doing this, I can't just be in this dark room playing my Call of Duty for six or seven hours, I just got a little schedule in," he said.
"I felt lost for the first couple of weeks but then it just flew by. I can't wait to get back out there.
"We've had a lot of gym sessions on Zoom, we've had our programmes being sent over to us, so I've been trying my best to keep up with the plan."
Newcastle boss Steve Bruce says starting before the end of June is simply not viable, insisting an earlier start would see them "fall down like a pack of cards".
"We've listened to what has been said and, with the precautions taken, we will get back to work and start phase one," Bruce said in the Sunday Telegraph. "Can we get to that stage where we can have all the players on the pitch together? We don't know yet.
"Phase one will be mainly fitness work, four or five players on a pitch. Let's see how we get on.
"You have to remember that they have had eight weeks off and that is probably the longest break some of these players have had in their careers.
"If we were doing pre-season, we would have six weeks and probably have six friendly games to get them ready for the first league match.
"So, we need a good stretch of time here to get them ready. Certainly once we get into stage two, that is vitally important. We need enough preparation to get these players into shape or they are just going to fall down like a pack of cards."
However, UEFA president Aleksander Ceferin believes most European leagues will be able to finish the season.
The German Bundesliga is the first major league to resume following the coronavirus pandemic while, along with the Premier League, plans are afoot for June resumptions in Spain and Italy.
France and Holland are the two major leagues who have opted to cancel their seasons.
UEFA has a plan in place, wanting to end the 2019/20 campaign with the Champions League final at the end of August, and Ceferin thinks that will be possible.
"We have a concrete plan of finishing the European season," he told beIN Sports. "Of course, this summer we will have to play without spectators at the stadiums.
"I think the majority of leagues will finish the season. The ones who will not, it's their decision. But they will still have to play qualifiers if they want to participate in the European UEFA competition.
"I can say that the European season will be finished, if everything is as it is now, in August. As things look now, I'm sure... that we can finish the European season and this means UEFA competition.
"The national leagues are a separate thing and they will decide separately how they want to proceed. But I think at least 80 per cent will finish the season."
Ceferin hailed the German league and Government for their organisation of the Bundesliga's resumption.
Play in Germany started on Saturday behind closed doors and appears to have been a success.
"We trust Germans, their authorities are very serious... It's not only about football," Ceferin said.
"It's about people being depressed because we are locked down, because there is so much uncertainty, and football brings life to a usual level.
"Football brings positive energy. It's easier to be home if you can watch sports!
"So I think it's a great [example of] cooperation between the German league and the German government. I hope, and think, they will be very successful."
LaLiga will step up its preparations for a return to action, with group training of up to 10 players allowed from Monday.
Spain's top two leagues are hoping to resume on June 12 and this marks a significant moment of progression.
- TEAMtalk media