![US Open Tennis on Twitter: "On this day in 1980, 🇺🇸 John McEnroe became @atptour World No. 1 for the first time. McEnroe passed rival Bjorn Borg in the rankings, on the US Open Tennis on Twitter: "On this day in 1980, 🇺🇸 John McEnroe became @atptour World No. 1 for the first time. McEnroe passed rival Bjorn Borg in the rankings, on the](https://pbs.twimg.com/media/EvjEZ1eXcAQq-Wd.jpg)
US Open Tennis on Twitter: "On this day in 1980, 🇺🇸 John McEnroe became @atptour World No. 1 for the first time. McEnroe passed rival Bjorn Borg in the rankings, on the
![January 7, 1979: The day 16-year-old Tracy Austin crushed Martina Navratilova to win the Avon Championships %%page%% - Tennis Majors Tennis: The day Tracy Austin beat Martina Navratilova January 7, 1979: The day 16-year-old Tracy Austin crushed Martina Navratilova to win the Avon Championships %%page%% - Tennis Majors Tennis: The day Tracy Austin beat Martina Navratilova](https://assets.tennismajors.com/uploads/2021/01/Tracy-Austin-01_07-OTD.jpg)
January 7, 1979: The day 16-year-old Tracy Austin crushed Martina Navratilova to win the Avon Championships %%page%% - Tennis Majors Tennis: The day Tracy Austin beat Martina Navratilova
United States Tennis Association - USTA (Official) - In 1979, she became the youngest US Open female singles champion in history... Happy Birthday, Tracy Austin! 🎉 | Facebook
![US Open 1979 Poster on Display at the Billie Jean King National Tennis Center Editorial Stock Photo - Image of competition, flag: 35563243 US Open 1979 Poster on Display at the Billie Jean King National Tennis Center Editorial Stock Photo - Image of competition, flag: 35563243](https://thumbs.dreamstime.com/b/us-open-poster-display-billie-jean-king-national-tennis-center-new-york-august-august-new-york-35563243.jpg)
US Open 1979 Poster on Display at the Billie Jean King National Tennis Center Editorial Stock Photo - Image of competition, flag: 35563243
![Bucharest, Romania, 1979. Romanian tennis player Traian Marcu during a match against Sweden in the Davis Cup tournament Stock Photo - Alamy Bucharest, Romania, 1979. Romanian tennis player Traian Marcu during a match against Sweden in the Davis Cup tournament Stock Photo - Alamy](https://c8.alamy.com/comp/2JB036K/bucharest-romania-1979-romanian-tennis-player-traian-marcu-during-a-match-against-sweden-in-the-davis-cup-tournament-2JB036K.jpg)
Bucharest, Romania, 1979. Romanian tennis player Traian Marcu during a match against Sweden in the Davis Cup tournament Stock Photo - Alamy
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