Nick Kyrgios overcame the early distraction of an incorrect line call to serve his way into the second round of the Cincinnati Masters.
The Australian No.1 said he wasn't overly pleased with his serve in his 7-5 6-4 victory over Italian Lorenzo Sonego in one hour and 19 minutes.
Kyrgios only served four aces but did not face a break point against Turkish Open champion Sonego and won 46 of his 54 service points, as he bounced back from his early exit last week in Montreal.
"I actually felt as if I didn't serve my best today at all. I'm being serious. I didn't feel like I was hitting my spots well at all," Kyrgios told Tennis Channel.
"I'm just happy to get through. I knew it was going to be tough and I wanted to play Khachanov next, so I'm looking forward to it."
The world No.27 will face eighth-seeded Russian Karen Khachanov for the first time, with a spot in the round of 16 up for grabs.
Two years ago, Kyrgios advanced to his maiden ATP Masters 1000 final in Cincinnati, falling to Grigor Dimitrov in the championship match.
On Monday, Kyrgios voiced his displeasure after a line judge mistakenly called his floated forehand crosscourt out in just the third game of the match.
Despite being distracted by the incident, threatening to walk off the court if another error was made by the officials and receiving a code violation warning for smacking a ball into the stands, Kyrgios broke in the 11th game of the first set and served it out clinically.
He broke early in the second set and wowed the crowd with an outrageous backhand volley winner off a full-blooded Sonego forehand return to take a 3-1 lead, which he celebrated by bowing after his effort.
Earlier in the day, Jordan Thompson lost to Japan's Yoshihito Nishioka 7-5 5-7 6-4 in the first round.
Thompson battled hard for two hours and 23 minutes but it was the Japanese qualifier who won the crucial points to claim a third three-set win over the Australian in their three career encounters.
Marin Cilic became the first seed to lose in this year's tournament when 39th-ranked Radu Albot beat him 6-4 7-6 (8-6) while Frenchman Richard Gasquet ousted Andy Murray 6-4 6-4 in the Scot's return to singles play after hip surgery.