Serbia's Novak Djokovic was upset in his opening match here Wednesday at the Paris Masters by American Sam Querrey, who rallied for an 0-6, 7-6 (7-5), 6-4 victory in just over two hours.

Despite the loss, Djokovic, the current world No. 2, is assured of finishing the year No. 1 no matter what happens at next week's season-ending World Tour Finals in London.

The early exit of Djokovic, who took the court wearing a Darth Vader Halloween mask, and world No. 1 Roger Federer's withdrawal due to nagging injuries have left the tournament wide open.

Scotland's Andy Murray, the U.S. Open champion and world No. 3, is now the tournament favorite, while Spanish world No. 5 David Ferrer will have a golden chance to capture his first-ever title at an ATP World Tour Masters 1000-level event.

Next up for Querrey will be the winner of the match between Canada's Milos Raonic and France's Jeremy Chardy. EFE