Sabalenka, a Belarusian, opened play on a sweltering Friday morning at Flushing Meadows and wasted little time making her intentions clear, breaking early to seize control and never looking back as she wrapped up the opening set.
"It's the first time I play morning session and it's a full stadium, I'm so grateful; it's a dream," a smiling Sabalenka said on court.
The world number one unleashed her trademark power from the start, firing down a dominant serving display with four aces and dropping just four points on her first serve.
The only hitch for Sabalenka during the opener came when a strong smell of cannabis drifted onto the Louis Armstrong Stadium court, briefly disrupting play as she alerted umpire Eva Asderaki-Moore.
In the second set, Sabalenka found herself having to work harder for her holds as Rakhimova shook off the tension and made the top seed earn her way through her service games, while saving four break points of her own.
But Sabalenka eventually found the opening she needed, producing a blistering return to earn the decisive break before serving out the victory.
"She played incredible in the second set, pushed me so hard and motivated me to bring out my best," Sabalenka added.
"I'm happy I closed this match in two sets."
Sabalenka, who has now won 16 straight matches at the US Open, is seeking to become the first woman since Serena Williams, who won three straight titles from 2012 to 2014, to complete a hat-trick of US Open crowns.
She will next face American Taylor Townsend, or Diana Shnaider in what would be a rematch of the French Open quarter-final match she lost against the Russian.
Meanwhile, Jessica Pegula kept alive her bid for a maiden Grand Slam title when the third-seeded American rallied from behind to beat fellow former US Open finalist Leylah Fernandez 1-6 6-4 6-3 and make the fourth round at Flushing Meadows on Friday.
Pegula faces Sorana Cirstea in the last 16 and will need to iron out some of the flaws in her game after a sluggish start against Fernandez, but the American showed the resilience and composure that have made her one of the title contenders.
"It was really tough today. I always feel it's hard to play her. I never feel comfortable when I play her, even when I have won," Pegula said.
"I was going to have to dig deep. I'm glad I was able to find somewhere there in the second set to turn it around. She's a great player, so it was really hard. A lot of it revolves around my serve. My serve percentage was pretty bad."
The Canadian dominated play with her left-handed aggression as she pushed 2024 runner-up Pegula back with deep groundstrokes while mixing up the pace and angles to take the opening set in 30 minutes.
Pegula responded strongly by breaking in the sixth game of the second set and then dug out a crucial hold in the following one before Fernandez mounted a fightback, but the American recovered to force a decider.
"I do think she played a bit differently today to when I've played her in the past," Pegula added.
"I wasn't moving my feet up to the ball, and was a little lazy to start off. Even in the second set, I felt I was hitting a bit of a wall after we played those two games."
The 32-year-old saved breakpoints early in the third set and pounced for a 3-1 lead when Fernandez sent her shot wide, before easing through the following games and sealing victory with a backhand volley winner on match point.
