The 19-year-old pacer achieved the feat against Sri Lanka in the first of the three-match T20I series against Sri Lanka.
He picked up a wicket on the final ball of the 16th over and two more on the first two balls of the 19th over.
The disconnect between the first and other two wickets meant that his feat was largely lost on the crowd and even the commentary team.
It was only after he had completed his hat-trick, it dawned that he has three in three balls.
Hasnain finished with figures of 3-37 in his four overs. Although he was wayward at the start, he came back strong and made his wicket-taking ability erase most of what had happened earlier.