Very nice stamp.
Martina Hingis (born Martina Hingisová; 30 September 1980) is a Swiss former professional tennis player. She spent a total of 209 weeks as the singles world No. 1 and 90 weeks as doubles world No. 1, holding both No. 1 rankings simultaneously for 29 weeks. She won five Grand Slam singles titles, thirteen Grand Slam women's doubles titles, winning a calendar-year doubles Grand Slam in 1998, and seven Grand Slam mixed doubles titles; for a combined total of twenty-five major titles. In addition, she won the season-ending WTA Finals two times in singles and three times in doubles, an Olympic silver medal, and a record seventeen Tier I singles titles.