Error-Prone Djokovic Survives Scare, Serena Rocks On

MELBOURNE — Novak Djokovic's grip on the Australian Open title looked shaky for a short spell on Sunday but the world number one finally shook off Gilles Simon in a four-and-a-half hour marathon to take his place in the quarter-finals.

Serena Williams, by contrast, booked a re-match of last year's title decider against Maria Sharapova by sweeping into the quarter-finals without having lost a set, and Roger Federer progressed almost as comfortably to bring the day to a close.

The whiff of an upset hung around Melbourne Park for much of the day -- Tomas Berdych, Agnieszka Radwanska and Carla Suarez Navarro all lost opening sets -- but it was most potent in Djokovic's five-setter against Simon.

Dj…