Clearly, even the Premier League and world champions have a limit.
And Liverpool discovered theirs on a dismal night that has made the next few weeks that little bit more difficult for Jurgen Klopp.
Perhaps the Reds boss should have known better than to expect his team to secure the win that would have earned progress to the Champions League knockout stages with two games to spare.
After all, little this season has gone serenely, while his team have a habit of doing things the hard way when negotiating the competition’s group phase.
This, though, underlined there is not an infinite resource among the Anfield squad, no matter how impressively their patched-up side dismissed Leicester City three days earlier.
Klopp again made further five changes, rotating out Fabinho, Roberto Firmino, Andy Robertson and Diogo Jota.
But as the four waited on the touchline to be introduced on the hour, Liverpool fell behind to a Josip Ilicic goal which was added to three minutes later by a similar Robin Gosens strike.
The only surprise is a near full-strength Atalanta, far more robust than the meeting three weeks ago, hadn’t already scored more.
By contrast, the Reds’ attacking effort was alarmingly insipid – tired, weak and bang out of ideas. Indeed, having scored five in Italy, they could muster only four shots here. None were on target.
Klopp has regularly espoused the importance of taking one game at a time, an approach that has helped Liverpool sweep up the honours in recent seasons.
This, though, is a campaign unlike any other, and his selection was dictated by the unremitting schedule, one eye no doubt on Saturday’s early visit to Brighton and Hove Albion.
He gambled. It backfired.
Liverpool still lead Group D with nine points ahead of Ajax and Atalanta, who both have seven.
And even if they fail to earn the required draw next week against the former, they still have the safety net of the away clash against group whipping boys FC Midtjylland.
Those games could have been used to continue rotating and resting players.
Now Klopp will surely have to go strong to make sure there are no further horror shows like this one.
