Lovlina Borgohain will take on Chinese Taipei's fourth seed Nien-Chin Chen next.
Lovlina Borgohain (69kg) advanced to the quarter-finals of women's boxing in her debut Olympics appearance, defeating German veteran Nadine Apetz in a closely-fought last-16 stage bout, in Tokyo, Tuesday.
The lone Indian boxer in action on the day prevailed 3-2 over an opponent 12 years her senior.
She will next face Chinese Taipei's fourth seed Nien-Chin Chen, who is a former World champion, on July 30.
Victory over the Chinese will assure Borgohain at least a bronze medal at the mega-event.
Chen, a silver-medallist at the 2019 Asian Championships, defeated Italy's Angela Carini 3-2 in her pre-quarter-final bout.Both boxers were making their Games debut and the Indian became the first from the country's nine-strong team to make the quarter-final stage.
The 23-year-old showed great poise in a tense contest to triumph by the thinnest of margins. She claimed all the three rounds on split points.
The 35-year-old Apetz, a two-time World Championships bronze-medallist and former European champion, was first German woman to qualify for a boxing event at the Olympics.
Borgohain is a two-time World and Asian Championships bronze-medallist. The youngster from Assam was the aggressor in the opening round before she changed strategy to play the waiting game.
It worked out just fine despite the German's well-placed jabs often troubling the Indian.
Borgohain relied mostly on her left hooks to keep the slender edge.
Apetz, who made the Games cut after reaching the semi-finals of the European Qualification Tournament last year, is a pioneering name in German boxing. She is pursuing a PhD in neuroscience, which she put on hold for a year to prepare for the Olympics.