Haaland scored twice in the second half of Saturday's match, with Marco Rose's side going on to defeat Mainz 3-1.
One particular BVB fan at the Westfalenstadion, Dortmund, watched in eager anticipation, before jumping out of his seat and running onto the pitch to celebrate with the young Norwegian.
The pitch invader was feeling particularly bold as he strolled towards the man of the hour.
But nobody at the Signal Iduna Park could have predicted what would happen next.
Before stewards could intervene, Haaland politely obliged his request for a selfie, then proceeded to celebrate wildly with the unnamed individual.
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Luckily for everyone that was not at the German top flight game, one reporter caught the hilarious exchange on camera.
When it was posted on Twitter, the caption read: "Incredible scenes in front of 64,000 fans in Dortmund after Erling Haaland scores two goals and makes a Borussia fan (who invaded the pitch) very, very happy!"
The video was retweeted by various football accounts and quickly wrapped up more than 200 retweets and 1,000 likes as of Saturday night.
Check out the video below:
Speaking after Haaland's performance against the 05ers, fellow goalscorer Marco Reus admitted 'it is clear he had been missing in our team'. Haaland scored twice on his return since recovering from a muscle injury.
"It is clear he had been missing in our team," said Reus, who opened the scoring.
"It is important that he plays because he constantly keeps two or three players occupied.
"To score two goals on his comeback is top. That is why we signed him."
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