The 18-year-old notched her second notable victory in two days at the Yonex BWF World Badminton Championships on Tuesday to claim her place in the next round.
In a marathon 69-minute tussle, Marin outlasted 15th seed Eriko Hirose of Japan 21-23 21-16 21-16.
On Monday, the Spaniard had beaten another much more experienced performer in the shape of Yao Jie of the Netherlands with a 21-18 23-21 scoreline.
Marin's whole-hearted style has been catching the eye for some time. In 2009 she won gold at the European under-17 championships and silver at the European juniors.
Last year she was one of several Europeans at the Youth Olympic Games in Singapore where she reached the quarter-finals.
Marin's badminton journey started when a friend in her home town of Huelva in Andalucia told her the sport was played there.
"I'm so pleased she got me started," said Marin, who now trains at the national centre in Madrid. "I'm far from my family but they are happy for me."
The Spaniard knows she is still learning but has ambition.
"My aim for this year is to get more experience at this tournament. After that my goal is to play at an Olympic Games and get a medal."
The International Olympic Committee (IOC) is celebrating one year on from Singapore 2010 this weekend from Friday 12 August, and will be running a number of stories on olympic.org and their official social media platforms. Also re-live the 2010 Youth Olympic Games on youtube.com/olympicsingapore2010.