Nick Kyrgios plays a backhand.

Nick Kyrgios plays a backhand. Photo: Mark Kolbe

UNFIT and overweight, Canberra teen Nick Kyrgios seemed to be nowhere near winning an Australian Open junior boys title a year ago.

But a change in mindset and a lift in training resulted in the 17-year-old joining the likes of fellow Australians Bernard Tomic and Luke Saville as junior champion in a grand slam tournament. In an all-Australian final, Kyrgios overcame his good friend and doubles partner Thanasi Kokkinakis 7-6 (7-4), 6-3.

It was revealed after the match that Adelaide 16-year-old Kokkinakis almost pulled out of the final after scans on Friday night revealed stress fractures in his back. While Kokkinakis battled bravely and had three set points in the first set, Kyrgios was a class above, living up to his ranking as the world No.1 junior.

Nick Kyrgios of Australia celebrates with the championship trophy. Click for more photos

2013 Australian Open Junior Boys Final

Nick Kyrgios of Australia celebrates with the championship trophy. Photo: Ryan Pierse

  • Nick Kyrgios of Australia celebrates with the championship trophy.
  • Nick Kyrgios serves.
  • Nick Kyrgios.
  • Nick Kyrgios of Australia celebrates a point.
  • Thanasi Kokkinakis during a break in his junior boys' final match against Nick Kyrgios.
  • Thanasi Kokkinakis.
  • Nick Kyrgios of Australia plays a backhand.
  • Nick Kyrgios celebrates winning his junior boys' final match against Thanasi Kokkinakis.
  • Nick Kyrgios of Australia poses with the trophy after defeating compatriot Thanasi Kokkinakis in their junior boys' singles final match.

Kyrgios said he performed below expectations at the tournament last year. The disappointment prompted him to join the Australian Institute of Sport program, resulting in a loss of five kilograms.

''I always had that ball-striking there but I knew I had to work hard and shed a bit of weight and obviously it's been paying off,'' Kyrgios said. ''I still love my food, I'm just training a bit harder.

''I'm pretty stoked with the last two weeks I've had, winning the lead-up tournament and now the Australian Open. It's a great start to the year.''

Kokkinakis didn't want to use the injury as an excuse. ''It hurt when I had to push off and change direction and when I had to bend my back and push off … but he put me in those positions,'' he said. ''He was too good. To beat a player like Nick, it's hard enough when you're 100 per cent healthy.''