By Erik Gudris

(October 31st, 2012) -- In a match that may have felt like "Trick or Treat" at times for both men on court, Sam Querrey upset top seed Novak Djokovic in a Halloween surprise at the BNP Paribas Masters in Paris.

Stepping onto court wearing a Darth Vader mask in honor of the holiday, Djokovic proceeded to completely dominate Querrey in the first set with the American only managing to win 10 points in a 6-0 rout. But an "embarrassed" Querrey as he later described himself got things going in the second set as he traded breaks with Djokovic before a tiebreak was needed to decide the set.

Querrey won the tiebreak seven points to five and pushed things into a decider with Djokovic looking more fatigued as the match went on. Querrey earned a crucial break midway through the set and soon jumped out to a 4-3 lead. Djokovic did have several chances to break in the next game but Querrey, who hit 18 aces total, used his big serve to fight off Djokovic and eventually close out a 0-6, 7-6(5), 6-4 victory.

The win is the biggest of Querrey's career since defeating Andy Murray in the finals of Los Angeles back in 2010.

Djokovic, who earlier in the week dealt with a mild illness before the event started, admitted he had not been in the best shape physically or mentally as he's also had to focus on his sick father with Djokovic flying to and back from Serbia to visit him.

"I've had a difficult past few days and I could feel it straight away in the second set. I just had nothing left," said Djokovic in his press conference. "These were personal problems that I don't really want to talk about right now but looking on the bright side, this at least gives me some extra days off to recover and prepare for the end of the season."

Djokovic will next compete at the Barclays ATP World Tour Finals in London.

(Photo Credit: Stephen Dunn/Getty)