World number one Sabalenka, stunned by Madison Keys in the 2025 final, ultimately had too much power, guile and quality for French wildcard Tiantsoa Rakotomanga Rajaonah.
But the Belarusian took time to find her touch, making a series of unforced errors before taming the spirited 20-year-old 6-4, 6-1 on Rod Laver Arena.
“It is always tricky playing someone young, someone you don’t know, and a lefty (left-hander),” said the top seed and title favourite.
Sabalenka said she had felt added pressure with tennis legends Roger Federer and Rod Laver court-side.
“I hope you guys enjoyed watching me play, I hope you enjoyed it even a little bit,” she said in her on-court interview, addressing the duo.
Sabalenka faces Anastasia Pavlyuchenkova of Russia or Chinese qualifier Bai Zhuoxuan next.
Title rivals Iga Swiatek and Coco Gauff begin their campaigns on Monday.
Earlier, in hot and sunny conditions, Zverev threatened to implode in losing the first set to Canada’s 41st-ranked Gabriel Diallo.
But the 28-year-old recovered from the shock to win 6-7 (1/7), 6-1, 6-4, 6-2 and next meets home player Alexei Popyrin or Alexandre Muller of France.
Asked how he reset from his first-set wobble, the third seed and last year’s losing finalist said: “I was thinking it can’t get worse than that.”
Also safely through was seventh-seeded Italian Jasmine Paolini as she outclassed Belarusian qualifier Aliaksandra Sasnovich 6-1, 6-2.
Elina Svitolina, the Ukrainian 12th seed, eased past Cristina Bucsa of Spain 6-4, 6-1.
But the seeds did not have it all their own way.
British qualifier Arthur Fery scored an upset by taking down 20th seed Flavio Cobolli of Italy, 7-6 (7/1), 6-4, 6-1.
Ukraine’s 26th seed Dayana Yastremska was another surprise casualty, losing 6-4, 7-5 to Romania’s Elena-Gabriela Ruse.
Also gone at the first hurdle was another Ukrainian seed, Marta Kostyuk, defeated in three sets by Elsa Jacquemot. (AFP)
