The German, who lost in three sets to Jannik Sinner in the 2025 tournament decider, ground past 41st-ranked Canadian Gabriel Diallo 6-7 (1/7), 6-1, 6-4, 6-2 on Rod Laver Arena.
It put him into round two at Melbourne Park for a tenth straight year as he looks to disrupt the domination of Sinner and world number one Carlos Alcaraz, who have shared the last eight major titles.
But he had to work hard to tame the lanky 24-year-old, who showed his potential with a maiden ATP title last year.
"Definitely wasn't happy when I saw the draw," he said.