From nine events in six countries in 1977 to 448 tournaments in 125 countries in 2016; that is how far the ITF Junior Circuit has progressed in its history.
The Junior World Ranking circuit was started by the ITF in 1977, linking nine of the major events for juniors. John McEnroe won all three tournaments he played, but finished third on the overall standings behind fellow American Van Winitsky. Czech Hana Strachanova headed the girls' year-end standings.
The following year the ITF started the Junior World Rankings and the Czech pairing of Ivan Lendl and Hana Mandlikova became the first Junior World Champions. Both players went on to achieve huge success in the senior game. Lendl, who held the world No. 1 ranking for 270 weeks, won eight Grand Slam titles, while Mandlikova went on to win the Australian, US and French Open crowns.
The next future Grand Slam champion to top the Junior World Rankings was Australian Pat Cash in 1981. Runner-up to Matt Anger in the 1981 Junior Wimbledon final, he went on to capture the senior event in 1987 with a memorable victory over Ivan Lendl.
Sweden's Stefan Edberg created history in 1983 when he became the first and only player to date to complete a Junior Grand Slam. He went on to become world No. 1 in 1990, and enjoyed six senior Grand Slam successes. Only the French Open remained beyond his reach as a professional.
Gabriela Sabatini of Argentina became the youngest girls' champion at 14 in 1984, with five tournament wins including the French Open and Orange Bowl. She went on to defeat Steffi Graf in the 1990 US Open final for her one senior Grand Slam success.
Chile's Marcelo Rios showed signs of a bright future when he topped the end-of-year rankings in 1991, and seven years later he became senior world No 1.
Martina Hingis emerged as the youngest player to capture a junior Grand Slam title when she won the French Open at the age of 12 in 1993. The following year she regained her Paris title, won at Wimbledon and took over as the youngest World Junior Champion. The Swiss player won a total of five senior Grand Slam singles titles.
Heading the end-of-year rankings in recent years have been 14-year-old Anna Kournikova in 1995, Australian Open and Wimbledon champion Amelie Mauresmo in 1996, and Wimbledon semi-finalist Jelena Dokic in 1998. Roger Federer became the boys' singles World Champion in 1998 claiming the Wimbledon singles and doubles and the Orange Bowl titles en route to the crown and finishing runner-up to David Nalbandian at the US Open.
It took Andy Roddick just three years to make the step from year-end junior No.1 in 2000 to year-end No.1 in the professional game in 2003. The US Open title helped Roddick to the top in both the junior and professional game; in juniors the American also won the Australian Open and the Banana Bowl.
More recently, 2005 Victoria Azarenka made her mark on the professional circuit, with Azarenka having reached the world No. 1 ranking after winning her maiden Grand Slam title at the Australian Open.
The Top 10 Club was introduced onto the Junior Circuit in 2006 and has some of the most recognised names in tennis amongst its members who receive exclusive benefits as recognition of their acheivements. Members include the likes of Bernard Tomic and Caroline Wozniacki.
The latest group of players looking to make the transition from the junior to pro circuit include Laura Robson, Ashleigh Barty, Eugenie Bouchard, Jiri Vesely and Tayor Fritz all of whom have impressed in winning junior Grand Slams and look set to be stars of the future.