Roundup: Djokovic, Zhang through to Australian Open fourth round

MELBOURNE, Jan. 21 (Xinhua) -- Nine-time champion Novak Djokovic battled ongoing hamstring issues to showcase trademark resiliency in his straight-set victory over Grigor Dimitrov on Saturday, while China's highest ranked player Zhang Shuai stormed into the Australian Open fourth round.

The fourth seed Djokovic continued his near invincibility at his favored Rod Laver Arena with a gritty 7-6 (7), 6-3, 6-4 victor