Novak Djokovic, Andrey Rublev tested in opening wins in Australia

(Photo credit: Geoff Burke-USA TODAY Sports)
World No. 1 and top seed Novak Djokovic opened the defense of his Australian Open championship with a win Sunday, but 18-year-old Croatian Dino Prizmic made him work for it in Melbourne.

The Serbian, seeking his 25th major victory, needed just over four hours to defeat Prizmic 6-2, 6-7 (5), 6-3,6-4 in his first main-draw appearance at a major. Prizmic, a qualifier, led 3-2 and