Sabalenka had unfinished business with the Canadian, who stunned Sabalenka in straight sets in the 2021 semi-finals en route to her runners-up finish in their only previous meeting.
There would be no repeat of that shock on Friday, with Sabalenka overcoming early jitters on Louis Armstrong Stadium, surviving a marathon opening game that featured three break points before finding her rhythm.
Fernandez refused to go quietly and forced a second-set tiebreak before the Belarusian's power prevailed.
Sabalenka's victory extends her perfect US Open third-round record to 6-0. The win also brings her within four victories of matching Serena Williams' feat of winning consecutive US Open titles achieved more than a decade ago.
"I really wanted this revenge," Sabalenka said in her on-court interview. "I'm very happy with the win."
There was also a proposal during her match which brought a smile to the world No.1.Â
Earlier, with ruthless efficiency, Elena Rybakina and Marketa Vondrousova powered towards a last-16 showdown between two former Wimbledon champions.
A year after shoulder surgery forced her to pull out at Flushing Meadows, Vondrousova delivered a shock of sorts on Friday as she knocked out the seventh seed Jasmine Paolini 7-6 (7-4) 6-1 on Grandstand Stadium.
The boilover came a couple of hours after Rybakina also reminded everyone why she's also a livewire contender to lift a second grand slam title as she dismantled the dream of rejuvenated former champion Emma Raducanu.
The Kazakh ninth seed advanced to the last-16 for the first time in her career with a merciless 6-1 6-2 victory on Friday in a match where the 2022 Wimbledon champ was expected to be given a tough examination from the Briton, who still can't rediscover the magic that propelled her to the 2021 US Open crown.
Vondrousova succeeded Rybakina as Wimbledon champ in 2023 and reached the US Open quarter-final later that year, but her striking revival has been interrupted by hand and shoulder injuries and only now is the left-hander again properly showing the quality that once took her to the 2019 French Open final as a teenager.
Paolini, a finalist at Wimbledon and Roland-Garros last year, had her chances in the opening set with a couple of break point opportunities but was outplayed in the tiebreak and in the second set.
Rybakina's victory over Raducanu turned, somewhat surprisingly, into a bit of a procession as the Kazakh earned early breaks in each set and controlled affairs to crack the Briton's serve four times in all in the 62-minute rout on Louis Armstrong Stadium.
"Yeah I'm really happy with the performance. It's always not easy to play against Emma," said the 26-year-old Rybakina.
"The score doesn't show it but she's a tough competitor. I'm pretty happy with the way I'm playing and I'm looking forward to the next match."
Raducanu tried to put a brave face on the crushing loss as her recent revival was checked ruthlessly.
"It's going to be important for me to just look at the last few months and weeks as a whole, and the improvements that I'm making, because a match like that can easily kind of get you down if you let it," she said.
No.4 seed Jessica Pegula beat Victoria Azarenka 6-1 7-5, but No.10 seed Emma Navarro and No.19 Elise Mertens both tumbled out.
Navarro went down 4-6 6-4 6-4 to Barbora Krejcikova while Mertens lost 3-6 7-5 6-3 to Cristina Bucsa.
The crowd then cheered Taylor Townsend who made the most of a spot in prime time at Arthur Ashe Stadium by upsetting fifth-seeded Mirra Andreeva 7-5 6-2.
Townsend is in the spotlight as a result of an interaction she wishes never took place with Jelena Ostapenko, who told the Black American she had "no class" and "no education" in a face-to-face argument after their second-round match.
With Reuters
