Monica Seles
Monica Seles
Men - Michael ChangWomen - Monica Seles
Monica Seles
I believe it was Michael Chang, 17 years old, French Open, 1989.
According to Wikipedia (refer to the link, below), Tracy Austin was the youngest player to win a U.S. Open match, and, subsequently, that Championship at 16 years, 9 months in 1979.
Jelena Ostapenko is the youngest women to win a grand slam at the 2017 French Open.
Men - Michael ChangWomen - Monica Seles
Martina Hingis was the youngest at 16 years 4 months in 1997.
Pete Sampras.
The Australian Open, French Open, Wimbledon and the US Open.
Donald Budge