World No 1 Novak Djokovic displayed steady recovery of his left shoulder injury on Tuesday by defeating an Australian challenger at the Japan Open, his first competition since pulling out of the US Open.

The experienced Serbian top-seed claimed a 6-4, 6-2 victory against 20-year-old Alexei Popyrin, who fought bravely at the Ariake Colosseum.

Popyrin mixed big serves with delicate drop shots to stage courageous offensives against 32-year-old Djokovic.

But Djokovic, taking part in a Japanese competition for the first time, kept his calm to always stay a step above the Aussie, never giving his opponent a break point while breaking once in the first set and twice in the second set.

Djokovic nailed seven aces, against eight by Popyrin, and managed to win points on 84 percent of his successful first serves. He finished the roughly 90-minute match by winning the final five games straight.

It was Djokovic’s first singles competition since he withdrew from his US Open fourth-round match against Swiss Stan Wawrinka due to a left shoulder injury.

As he prepared to take on the singles tournament, Djokovic played and lost a doubles match in Tokyo on Monday and said his shoulder felt “fine”. Wawrinka decided not to participate in the Tokyo tournament due to injuries.

Djokovic was marking his 271st week as the world No 1, claiming the title of the third longest weeks in the top spot, and passing the record of American great Ivan Lendle. The Serbian is now chasing Pete Sampras with 286 weeks, and Roger Federer with 310 weeks.

In the rest of the Tokyo tournament, Japanese wild card Taro Daniel, ranked 127, pulled off an upset victory against second-seeded Borna Coric of Croatia, ranked 14th, with a 6-4, 4-6, 7-6(7/5) win in a grueling match that stretched over two hours and 30 minutes.

Japanese qualifier Yasutaka Uchiyama defeated French fourth-seed Benoit Paire 6-2, 6-2.

Reilly Opelka of the US defeated his countryman seventh-seed Taylor Fritz 6-3, 6-4. Frenchman Gilles Simon cruised by Spanish qualifier Pablo Andujar 6-4, 6-0.