The Norwegian striker started the clash against Arsenal at Wembley but was substituted midway through the second half having barely made an impact, but that didn't stop him from firing shots at the Gunners' fans.
Making his way off the pitch to a chorus of boos from the Arsenal fans, Haaland held up three fingers which appeared to reference the three trophies won by Man City last term.
Haaland played a key role in the success of Man City's side last term as they won the Premier League, the FA Cup and the Champions League to become the first English side to win the treble since their rivals Manchester United did in 1999.
Over the course of the campaign, he scored 52 goals and provided nine assists for City on their way to glory.
But by the striker's own high standards, he's currently in one of the biggest droughts of his career so far.
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The 23-year-old has failed to score in his last six competitive appearances - a tally which takes on added significance given that he's never previously gone more than three games without scoring for the club.
He also failed to attempt a shot for the second time since joining last year, the other instance coming against Tottenham in February.
While no one is suggesting that Haaland has now lost his mojo, Arsenal fan Morgan couldn't resist sending a social media message to the City striker, simply writing: "Hi mate. @ErlingHaaland."