Melbourne - Top seed Novak Djokovic angrily blamed floodlights for dropping a set for the first time at this year's Australian Open after beating Denis Shapovalov 6-3, 6-4, 4-6, 6-0 on Saturday.
The Serb is looking for a record seventh Aussie crown but was left fuming when leading 3-0 in the third set against the 25th-seeded Canadian when the powerful lights blazed on all around Rod Laver Arena - in bright sunshine.
An irritated Djokovic lost his focus completely and dropped six of the next seven games after querying French umpire Damien Dumusois why the lights were on.
"I think there was no sense to turn on lights on court at 5pm when we have another four hours of daylight," fumed the Serb 17-time Grand Slam winner.
"Did you guys see the balls well?," he asked the crowd.
"I saw them well too," he said to a huge cheer.
"Completely unnecessary to turn on the lights. The explanation I got was for TV reasons. I hope the viewers enjoyed it," he added.
The normally mild-mannered Djokovic even received a code violation for verbally jousting with someone in the crowd who shouted "Nervous?", as he faced three break points at 4-4, 0-40 in the third set.
Up till his mini-meltdown, Djokovic had made his outing on centre court look like an afternoon practice session for two-and-a-half sets against Shapovalov, one of the NextGen stars tipped to take over from the sport's old guard
He skilfully dominated the 19-year-old, who could not find enough winners to throw the 14-time Grand Slam winner off his stride until a TV director's decision gave him a helping hand.
Djokovic took the opening stanza in a routine 35 minutes and looked as if he would easily extend his winning streak against left-handers at Grand Slams to 18 matches.
The last leftie to beat him at a major was Rafael Nadal in the final at Roland Garros in 2014.
Djokovic left the court at the end of the third set and came back a new man, unloading a massive primal scream to relieve his tension as he broke for 2-0 before closing out the whirlwind last set in a match that lasted 2hr 22min.
Djokovic's victory means he is guaranteed to stay world number one when the new rankings are released after the tournament.
He next plays another young gun, Russia's 22-year-old 15th seed Daniil Medvedev.