Bayern Munich star Robert Lewandowski has hit out at the demands placed on footballers in the modern era, insisting the schedule players face in the coming years poses a "big problem".
The Pole has made 46 appearances for club and country over the course of a 2020-21 campaign condensed by the coronavirus pandemic, and is set to add to that at Euro 2020.
The coming years are unlikely to be any easier, with a mid-season World Cup in Qatar coming up in 2022 and Champions League reforms set to add an extra four group games from 2024.
And Lewandowski is concerned that players are at risk of burnout as the demands on their bodies continue to build.
"So many people forget we're humans, we're not machines, we cannot play every day at the highest level of performance," he told The Times.
"For football and for young players, that will be the big problem, to stay at the top for many years, because now and maybe the next two years, that will be extreme: so many big games."
Lewandowski top scored with 15 goals as Bayern won the Champions League for the first time in seven years in 2019-20.
But he thinks the addition of extra fixtures to Europe's premier cup competition could ultimately ruin the spectacle for supporters.
"Even for the fans, I think so many games will be more boring because if you wait for the games longer, there's more expectation, that feeling that you've been waiting for this," he added.
"The quality of games will go down. It's not possible to stay with this quality on the top with so many games."
Lewandowski's own form showed no sign of fading amid the 2020-21 schedule as he broke Gerd Muller's long-standing Bundesliga record for goals scored in a single season with his 41st top-flight strike of the campaign in Bayern's win over Augsburg.