champion Andy Murray Tokyo - Agencies Defending champion Andy Murray blew away the cobwebs with a 7-6, 6-4 win over Croatian Ivo Karlovic Tuesday in his first tennis match since winning last month’s U.S. Open. The Olympic gold medalist said winning his first Grand Slam title had forced him to change his objectives and become more “responsible.” “I was so, I don’t want to say ‘obsessed,’ with winning a Grand Slam, but it was so important to me,” world No. 3 Murray told reporters. “Sometimes during the year in certain matches I haven’t done myself justice. I felt after the U.S. Open [I needed to] reset some goals. “I was always focusing on the next Grand Slam rather than every tournament and every match I played. “Now I feel like I can hopefully concentrate better, take more responsibility for my performances in every tournament throughout the year.” The Scot said he felt no different having finally won his first Grand Slam in New York after losing in four finals. “It didn’t feel a whole lot different [stepping on court as a Grand Slam winner],” said the 25-year-old. “Hopefully with time that will come,” added Murray, who reached his first Wimbledon final this year before exacting his revenge on Roger Federer in the Olympic final in London. “I think where I will feel it more will be if I’m getting to the latter stages of Grand Slams. Hopefully I will start feeling more confidence to go on to win.” Murray had been scheduled to open his Japan Open defense against Gael Monfils but the Frenchman pulled out with a knee injury, to be replaced by lucky loser Karlovic. Murray, who was on court for an hour and 38 minutes, will face Slovakia’s Lukas Lacko in the second round. Meanwhile, Novak Djokovic made a rusty return to action at the China Open, as second seed David Ferrer retired with illness and women’s world No. 1 Victoria Azarenka stormed into the third round. The Serbian world No. 2, playing his first match since losing last month’s U.S. Open final to Murray, beat German qualifier Michael Berrer 6-1, 6-7 (3/7), 6-2 in the men’s first round, but the performance was far from impressive. Djokovic, 25, took the first set with ease but lost the second on a tiebreak after hitting several unforced errors against the 123rd-ranked left-hander, before improving his groundstrokes for the decider. “I had a tough time to really return his serve in the second [set], because he went for precision more than the speed of his first serves,” Djokovic said. “He had a very high percentage of first serves in and he put a lot of pressure on my serves. I tried to stay closer to the line in the third, and it worked,” he added. The No. 1 seed has won China’s Open on the two occasions he has entered, in 2009 and 2010, but missed last year because of injury. Elsewhere, Spain’s Ferrer retired due to illness during the first set of his match against Taiwan’s Lu Yen-Hsun, and third seed Jo-Wilfried Tsonga of France battled to a three-set victory over Uzbekistan’s Denis Istomin. The world No. 7 lost the first set but came back to win 4-6, 6-1, 7-6 (7/3). Tsonga’s countryman Julien Benneteau, who lost in the final of the Malaysian Open just two days ago, was also forced to retire two games into the second set, handing Italy’s Andreas Seppi an easy route to the second round.