SYDNEY, Jan. 3 (Xinhua) -- Novak Djokovic was knocked out of the Brisbane International in a major quarterfinal upset, while fellow top seed Aryna Sabalenka won through to the semifinals on Friday night.
Djokovic was beaten 7-6 (6), 6-3 by world number 293 Reilly Opelka in one hour and 40 minutes in a late-night match on center court.
The big-serving American hit 16 aces on the way to claiming the biggest
