(Reuters) - Novak Djokovic overcame some early jitters in his first match since his triumph at Wimbledon last month to see off Sam Querrey 7-5 6-1 at the Cincinnati Masters on Tuesday. Aug 13, 2019; Mason, OH, USA; Novak Djokovic (SRB) returns a shot against Sam Querrey (USA) during the Western and Southern Open tennis tournament at Lindner Family Tennis Center. Mandatory Credit: Aaron Doster-USA TODAY SportsThe defending champion and world number one fired his 15th ace on match point to make up for his slow start on the sun soaked courts. \u201cI made three double faults in my opening game and lost the break. I was quite a nervous at the start,\u201d he said of falling behind 2-0 against the big-serving American. \u201cI\u2019m really glad to overcome a challenge like this and get myself going.\u201d Djokovic, who defeated Roger Federer in an epic final at Wimbledon, said he needed time to recover from the surge of emotions. \u201cThat was one of the most epic matches I\u2019ve been a part of and probably the most demanding one from the mental perspective,\u201d he said of his five-set victory. \u201cSo it really did take me some time to recharge my batteries, especially in my head. My body was fine.\u201d Swiss Stan Wawrinka overcame Bulgaria\u2019s Grigor Dimitrov 5-7 6-4 7-6(4) in a roller-coaster first-round match. Dimitrov clawed back from a double break down in the decider to level at 5-5 and after Wawrinka broke again, Dimitrov forced the tiebreak. The Swiss surged into a 4-0 lead but Dimitrov rallied once more before Wawrinka closed out the match with an ace. Young American Frances Tiafoe beat Frenchman Gael Monfils 7-6(7) 6-3 and Canadian Denis Shapovalov came from behind to see off Portugal\u2019s Joao Sousa 2-6 6-3 6-2. Reporting by Gene Cherry in Raleigh, North Carolina, editing by Ed OsmondOur Standards:The Thomson Reuters Trust Principles.