Sinner fell to a quarter-final defeat to Andrey Rublev at the Canadian Open in Montreal and was seen holding his hip at various stages of the encounter.
Nevertheless, the world number one said his only real concern was returning to the intensity of matches after skipping the Paris Olympics due to tonsillitis.
"I feel quite good. Obviously, I made nearly one week without practising before, and then after playing for two-three days in a row, a bit more than usual, (that) could (have had) a potential impact to the hip," Sinner told reporters.
"But I'm not afraid. I feel good with the hip, and I'm just looking forward to going back on court here."
Sinner holds a poor record in Cincinatti, having never advanced to the quarter-finals, and was the victim of a shock loss to Dusan Lajovic in the round of 32 last year.
However, the Italian is confident of a better run this time around, starting with an opening against either Tallon Griekspoor or Alex Michelsen.
"Here usually I struggle a little bit to play because of the conditions but I'm looking forward to see my reaction this year, because it's a great test," said Sinner.
The Australian Open champion believes a good tournament can act as a perfect platform for the final slam of the year in New York, which begins at the end of this month.
"I believe this tournament can give you a lot of confidence for the US Open, which is the last grand slam we have," Sinner said.
"So in my mind, this is a very important tournament. "We go day by day. I have a couple of days to prepare and hopefully show some good tennis."
Sinner fell to a quarter-final defeat to Andrey Rublev in Montreal last time out, appearing to struggle with a hip issue throughout that loss after missing the Paris Olympics due to a bout of tonsillitis.
However, the Italian played down any concerns over his fitness ahead of his last-32 match in Cincinnati, where he was pushed all the way by Michelsen but held firm to advance.
Sinner had to save eight break points in one hour and 52 minutes on court, committing as many unforced errors (19) as his American opponent.
However, breaks in the very first game of the opener and the penultimate game of the second set proved decisive for the Australian Open winner, who will now face either Sebastian Baez or Jordan Thompson for a quarter-final place.
Meanwhile, Stefanos Tsitsipas bounced back from his first-round Canadian Open exit at the hands of Kei Nishikori, fighting from a set and a break down to beat Jan-Lennard Struff 4-6 6-4 6-3.
Speaking after his win, Tsitsipas – who will face Jack Draper or Jaume Munar next – said: "I was down a break, and I managed to keep on fighting and get the break back.
"Suddenly I felt like I was starting to figure out what really worked behind his serve. He made a few double faults, and I took that chance, got myself in the lead, and I think once I started reminding myself of my best qualities as a player, these things really started working."
Data Debrief: Sinner looking to stay perfect
Sinner's victory improved his record on hard courts to 25-2 for the season, and a first quarter-final berth at Cincinnati is now within his sights.
He has reached at least the last eight at all five ATP 1000 Masters tournaments he has played this year, though his only such title came in Miami in March.
Sinner, who is aiming to secure a second grand slam of 2024, needed just an hour and 39 minutes to dispatch his American opponent, emerging a 6-4 6-0 6-2 victor.
The world number one navigated a difficult opening set, seeing his opening game break evaporate immediately before a break point in the ninth game gave him the early advantage.
Sinner would showcase his class in the second, dropping 11 points throughout the entirety of the set to go within touching distance of advancing to the third round.
Michelsen would match his opponent for the opening games of the third set, but a break in the fifth game proved decisive, with Sinner able to cruise to victory from then on.
The Italian's triumph set up a meeting with Australian Christopher O'Connell after overcoming a scare against Italian qualifier Mattia Bellucci in four sets.
Data Debrief: The Italian job
Sinner's triumph over Michelsen saw him achieve consecutive 50-win seasons at ATP level, becoming the first Italian in the Open Era to reach that number.
The world number one impressed on serve, winning 30 of his 37 first-serve points, while also hitting 23 winners compared to the American's 15.
