Martina Hingis is a former professional tennis player from Switzerland. She was ranked world number one in singles for a total of 209 weeks and won five Grand Slam singles titles. Hingis was the youngest ever Grand Slam champion when she won the 1997 Australian Open at the age of 16. She also won the Wimbledon women's doubles title in 1996 and 1998. Hingis retired from professional tennis in 2003, but returned to the sport in 2006. She retired again in 2007 and was inducted into the International Tennis Hall of Fame in 2013.