The 26-year-old Fritz is attempting to become his country's first male Grand Slam champion since Andy Roddick at the US Open in 2003.
He doesn't lack confidence, believing that defeating compatriot Frances Tiafoe in a five-set semi-final on Friday, where he was second-best for large parts of the evening, was more of a challenge than facing Sinner.
"I don't think that I'm going be put in a more stressful situation than I was against Frances," said Fritz, the first American man in a Slam final since Roddick at Wimbledon in 2009.
"I just feel good. I have a feeling I'm going to come out and play really well and win. When I play good tennis, I think that level is good enough to win."
World number 12 Fritz has capitalised on the huge hole left in the tournament by the shock early exits of four-time US Open champion Novak Djokovic and 2022 winner Carlos Alcaraz.
He did his part by seeing off fourth-ranked 2020 runner-up Alexander Zverev in the quarter-finals after defeating eighth seed and 2022 finalist Casper Ruud in the last 16.
He has a 1-1 head-to-head record against Sinner, the first Italian man to reach the US Open final.
Fritz won their first meeting on the hard courts of Indian Wells in 2021 with Sinner gaining revenge at the same California desert venue two years later.
"I've always played well against Jannik. He hits the ball big. He's like a very strong ball striker, but I feel like I always hit the ball really nice off his ball," explained the American, who had never got past the quarter-finals of a major before this US Open.
Sinner won his maiden Grand Slam title at the Australian Open in January and has shrugged off the controversy over two failed drugs tests to reach his second Slam final of 2024.
He has a perfect record of five wins in five finals in 2024, adding the Rotterdam, Halle, Miami and Cincinnati titles to his Melbourne triumph.
Sinner wrist worry
The 23-year-old also has 54 wins against just five defeats this season and he is relishing facing not just Fritz but also a boisterous 23,000-capacity crowd inside the cavernous Arthur Ashe Stadium.
"Being in America for sure, the crowd will be a little bit more on his side," said Sinner.
"But it's normal. It's like when I play in Italy, so I'm going to accept that.
"I have my team and my people who are close to me. In my mind, I know that there are many people watching from home from Italy, and it's just take some support from them.”
One concern for the Italian is the condition of his left wrist, which he hurt while breaking a fall during his semi-final victory over Britain's Jack Draper.
Sinner required a medical timeout to have the injury treated but was quick to quash concerns that it will be an issue on Sunday.
"The physio loosened it up very fast on court and it went away by playing, which is good," explained Sinner.
"Let's see how it is tomorrow when it's cold. It's going to be a different feeling. Hopefully it's nothing to be concerned about. I'm quite relaxed, because if it's something bad, you feel it straightaway a bit more."
Win or lose on Sunday, Fritz believes American men's tennis is on the brink of a new golden age as the country boasts five players in the top 20.
"I think it gives hope and shows that we're knocking on the door of winning a Slam," Fritz said.
"We're all moving in the right direction. I think that whenever one of us does something, the others follow, and the others get belief from it. I think this is just the start for all of us."
