India, Sept. 10 -- Two-time champion Nikhat Zareen survived a gritty test to edge past Japan's Yuna Nishinaka and progress to the quarterfinals of the World Boxing Championships here on Tuesday. Unseeded in the draw, Nikhat overcame a scrappy women's 51kg round of 16 contest to secure a unanimous decision, though the scoreline did not reflect the stiff resistance from her 21-year-old opponent. Nishinaka troubled the Indian with constant clinching and was docked two points for excessive holding. Both boxers started aggressively, surging forward with intent. Nikhat landed a couple of early hooks, but the round was fragmented by repeated tangles, and the Japanese fighter edged it 3-2 on the cards. In the second, Nikhat adjusted, landing clea...