Djokovic came through the longest first-round Grand Slam match of his career against teenage qualifier Dino Prizmic on Sunday, playing for four hours and one minute.
The early stages of his second match of the tournament suggested it would be a much quicker encounter for the Serb.
Dominant on serve, Djokovic took 38 minutes to claim the opener, sealing the decisive break with a stunning cross-court winner to go 5-3 up before consolidating.
However, Popyrin – the world number 43 – proved to be a bigger threat than rankings suggested.
Having gone a break up in the fourth game, Popyrin missed the chance to serve out the second set, but he redeemed himself in front of his home fans with a sensational lob to break at 5-4 and level the match.
Djokovic survived four set points before racing through the tie-break to close out a dramatic third set and put himself in the driving seat.
After a confrontation with a heckler in the stands, the 24-time major winner thrived on the crowd’s hostility to break for a 4-2 lead and, having missed out on four match points, he claimed victory with the fifth as the clock struck midnight at Melbourne Park.
“[I’m] still trying to find the form but as you said in the early rounds you play players with nothing to lose,” Djokovic said in his on-court interview.
“They come out on court to try and play their best tennis and I think both my first and second-round opponents were really great quality tennis players and I managed to find a way to win in four.”
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