By Julien Pretot PARIS, Oct 31 (Reuters) – Novak Djokovic dispensed with the Darth Vader mask but still proved too daunting an adversary for American John Isner as he reached the Paris Masters quarter-finals with a 6-7(5) 6-1 6-2 victory on Thursday. No Darth Vader,” Djokovic, who watched nine aces fly by him in the opener, told a news conference. Roger Federer showed glimpses of his brilliant best as the 17-times grand slam champion outclassed German Philip Kohlschreiber 6-3 6-4 to advance into the last eight. A day after securing his place at next week’s ATP World Tour finals, the Swiss was comfortable throughout as he set up a clash against Juan Martin del Potro who beat him in the Basel final last week.