In the past couple of years, Joe Hart's stock in the footballing world has plummeted.
But after some sub-par displays at Euro 2016 on international duty, the shot-stopper's career started deteriorating at a rapid rate.
The 34-year-old left City for Burnley in 2018, where he spent two unsuccessful years before joining Tottenham Hotspur.
It didn't work for him in north London either, which resulted in Hart moving to Celtic this summer.
At first, it looked as if the switch to Glasgow was exactly what the Englishman needed, but his error-free performances unfortunately haven't lasted too long.
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On Thursday night, Hart started in Celtic's Europa League qualifier away at AZ Alkmaar and in the sixth-minute of the game, he made a horrendous mistake.
Hart was painfully slow to react to a ball that was bouncing towards his penalty area, which allowed Zakaria Aboukhlal to swoop in and snatch it.
The Moroccan then finished the opportunity to make it 1-1 and cancel out Kyogo Furuhasi's opening goal for Celtic.
Take a look at Hart's error here...
Video: Hart's first Celtic howler
Why was Hart so slow to the ball?!
If the goalkeeper had just sprinted for less than a second, he would have been able to clear the danger with ease.
But Hart opted to stroll rather than sprint and that eventually resulted in Aboukhlal being presented with a chance that he simply could not miss.
Shortly before the half-time break, a Callum McGregor own goal put AZ Alkmaar 2-1 up on the night and only 3-2 behind on aggregate.
But Celtic managed to avoid conceding a third goal in Holland to secure a place in the group stage of this season's Europa League.