In tennis, who is the first and so far only player to achieve the "Junior Grand Slam"?

Stefan Bengt Edberg (born 19 January 1966) is a Swedish former professional tennis player. A major proponent of the serve-and-volley style of tennis, he won six Grand Slam singles titles and three Grand Slam men's doubles titles between 1985 and 1996. He is one of only two men in the Open Era to have been ranked world No. 1 in both singles and doubles (the other being John McEnroe).

He also won the Masters Grand Prix and was a part of the Swedish Davis Cup-winning team four times. In addition, he won four Masters Series titles, four Championship Series titles and the unofficial 1984 Olympic tournament, was ranked in the singles top 10 for ten successive years, and ranked 9 years in the top 5.

Edberg first came to the tennis world's attention as a junior player. He won all four Grand Slam junior titles in 1983 to become the first (and only) player to achieve the "Junior Grand Slam" in the open era. Later that year as a professional, Edberg won his first career doubles title in Basel.

The Junior Grand Slam titles are the Australian Open, French Open, Wimbledon and US Open.