Zverev holds off Nakashima to reach Indian Wells fourth round
Zverev didn't have a break point against the 30th-ranked opponent until the third set. He missed his first two opportunities before finally making one count, breaking Nakashima in the final game to seal the victory.
"He has an incredible serve, and you don't think about that," Zverev said of Nakashima, who fired 17 aces to the German's 15. "His placement on serve is probably the best in the world.
"What he's lacking in power he's definitely got in placement. I was not having any chances to break him for the first two and a half sets and the only chance I kind of had I used it in the end.
"Definitely happy to get the win because that was a difficult match," Zverev said.
The German gained the upper hand in a close-run contest with a dominant first-set tiebreaker, but the American converted his fifth break chance for a 6-5 lead in the second and leveled the match with a love game.
Zverev improved to 5-0 against Nakashima, a 24-year-old Southern California native who remembers watching Novak Djokovic and Roger Federer play Indian Wells as a youngster.
He'll face either 15th-seeded Italian Flavio Cobolli or American Frances Tiafoe for a place in the quarter-finals.
World number two Jannik Sinner headlined men's action on Sunday, taking on Canadian Denis Shapovalov.
Italy's Sinner aims to keep his quest for a first Indian Wells title rolling after dropping just two games in an impressive opener against Czech qualifier Dalibor Svrcina.
Eighth-seeded Ben Shelton takes on Learner Tien in an all-American Stadium Court clash.
But the real fireworks could come later, when American Tommy Paul faces 19-year-old Brazilian Joao Fonseca in the final match of the night.
Fonseca saved two match points in his second-round victory over 16th-seeded Karn Khachanov.
Paul, seeded 23rd, opened his campaign with a 6-1, 6-2 drubbing of Belgian Zizou Bergs.