Final answer:
Martina Hingis is the 16-year-old Swiss player who in 1997 became the youngest-ever winner of a Grand Slam tournament at the Australian Open.
Step-by-step explanation:
The 16-year-old Swiss tennis player who became the youngest-ever winner of a Grand Slam tournament in 1997 at the Australian Open is Martina Hingis. At such a youthful age, she made sports history by triumphing in singles at one of tennis' most prestigious events, showcasing remarkable talent and setting a record that is often cited in tennis lore. Hingis continued to have a successful tennis career, securing numerous titles and establishing herself as a dominant force in women's tennis during the late 1990s and early 2000s.