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."
Premier League clubs will vote on a return to training today.
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 explained.
"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 return 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. "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."
• Darron Gibson is one of 11 players released by Salford following the end of the League Two season.
Former Northern Ireland international Michael O'Connor has joined him through the exit door.
Clubs in English football's bottom tier signalled their intention to end the campaign on Friday and Salford are already looking to next season.
Former Republic of Ireland international Gibson, 32, played just four times for the club during their maiden Football League season. The Derry man joined Salford on a six-month deal in February having been released by Wigan Athletic at the end of the 2018-19 season.
Josh Askew, Craig Conway, Kieran Glynn, Kyle Letheren, Chris Neal, O'Connor, Nathan Pond, Devante Rodney, Mark Shelton and Scott Wiseman are the other players leaving the club. Ibou Touray has, however, had his contract extended to the end of the 2020/21 campaign.
Graham Alexander's side have finished in mid-table after the division was decided on points per game.