"I'm happy that I managed to raise my level in important moments, except a game in the second set," Medvedev said.
"It's great that I managed to still find in this tough match these moments of consistency, which is enough to win.
The 10th-ranked German has lost three times to Medvedev this year but flipped the script in their last meeting in Cincinnati.
I'm really happy with that.
The Tunisian, who is looking to qualify for the season-ending WTA Finals, plays Marta Kostyuk in the second round.
Persons:
Russia's Daniil Medvedev, France's Ugo Humbert REUTERS, Florence Lo, Daniil Medvedev, Ugo Humbert 6, Alexander Zverev, Medvedev, Humbert, Zverev, Chile's Nicolas Jarry, it's, He's, Carlos Alcaraz, Casper Ruud, Grigor Dimitrov, Jannik, Spain's Sara Sorribes Tormo, Frenchwoman Varvara Gracheva, I've, Swiatek, I'm, Coco Gauff, Ekaterina Alexandrova, Ashlyn Krueger, She's, Marta Kostyuk, Shrivathsa Sridhar, Clare Fallon
Organizations:
China, National Tennis Center, Rights, Chile's, Beijing, Thomson
Locations:
Beijing, China, Rights BEIJING, Rotterdam, Doha, Dubai, Miami, Russian, Chengdu, Cincinnati, Ningbo, Osaka, Bengaluru