TOKYO -- Coming off an injury, Novak Djokovic is confident his game is going in the right direction.
Top-ranked Djokovic, who is attempting to win a title on his tournament debut for the 10th time, hit 10 aces and saved three of four break points.
Djokovic retired with a left-shoulder injury during his fourth-round match against Stan Wawrinka at the U.S. Open but showed no lingering effects in Tokyo.
In his first competitive match since facing Wawrinka, Djokovic was knocked out of the doubles with Filip Krajinovic on Monday but beat Alexei Popyrin in the first round of the singles on Tuesday.
After three matches in three days, Djokovic said he's pleased with his progress.
"I probably played even on a higher level than the first round," Djokovic said. "So the game is going in the right direction, that's for sure. I've played three games in a row, the doubles on Monday then two straight singles matches back-to-back, so everything is fine."
With Djokovic serving for the win, Soeda broke his opponent for the first time when Djokovic double-faulted to make it 5-4. But the top-ranked Serb broke Soeda for the fourth time in the final game.
"From the baseline, I was solid, aggressive when I needed to be and taking the ball early," Djokovic said. "I served very well until that game when I was serving for the match at 5-3. I made some double-faults, I missed all my first serves, so I didn't serve that well that game, allowing him to break back and come back to the match.
"But there were not too many negatives today, because I had chances constantly. I had match points at 5-4, but he just came up with some very good shots and fought hard and that's why we give him credit. But from my side, I'm really pleased."
Djokovic, who is 42-8 this season with three titles in four finals, has a day off Thursday. He faces Lucas Pouille in the quarterfinals after the Frenchman beat Yoshihito Nishioka 6-1, 6-2.
Also, Yasutaka Uchiyama beat Radu Albot 6-7 (2), 6-3, 6-4 and Reilly Opelka defeated Gilles Simon 7-6 (4), 7-6 (2).
Third-seeded David Goffin rallied to beat Pablo Carreno Busta 1-6, 7-6 (8), 6-0 to advance to the second round and next faces Denis Shapovalov.
Goffin is the lone former champion in the draw. He has made the final in both of his previous appearances, losing to Nick Kyrgios in the 2016 final before defeating Adrian Mannarino for the title in 2017.
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