Jannik Sinner is confident the wrist issue that troubled him during Friday's US Open semi-final win over Jack Draper is "nothing to be concerned about" ahead of Sunday's final.

Sinner reached his first final at Flushing Meadows with an impressive 7-5 7-6 (7-3) 6-2 success over Draper, who had not dropped a single set en route to the final four.

While Draper vomited at the side of the court after struggling with anxiety, Sinner also called for medical attention after tweaking his left wrist in the second set.

The world number one stayed in a brutal rally despite falling awkwardly when playing a lob from deep on the court, then got up to slam a brilliant forehand winner past Draper.

He immediately received treatment on the affected wrist but showed few signs of discomfort from then on to become Italy's first-ever male finalist at the US Open.

"The physio loosened it up very fast on court, so after I felt okay in the beginning. Then after it went away by playing, which is good," Sinner told reporters after his win.

"Let's see how it is tomorrow when it's cold. It's going to be a different feeling. Hopefully it is nothing to be concerned about. 

"I'm quite relaxed, because if it's something bad, you feel it straightaway a bit more."

At the age of 23 years and 21 days, Sinner is the youngest man to reach the final at both the Australian Open and the US Open in a single year since the former event switched from grass surfaces in 1988, surpassing Roger Federer in 2004 (23 years, 34 days).

He will be up against a home favourite in Taylor Fritz on Sunday, and he accepts he will have to play the role of villain in the eyes of a raucous crowd at Arthur Ashe Stadium.

"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," he said.

"In my mind, I know that there are many people watching from home from Italy, and I'll just take some support from them."

Fritz rallied to beat compatriot Frances Tiafoe in five sets having been both 1-0 and 2-1 down in Friday's second semi-final, and he said reaching the showpiece match represented the realisation of a lifelong dream in an emotional press conference. 

"It's just how I am. I'm more of an emotional person when I'm happy. When I'm really happy I cry at happy endings of movies and not at sad stuff. That's just how I am," Fritz said.

"It's just joy, the crowd cheering and that realisation, like, 'wow, I'm in the finals of the US Open. 

"It's such a lifelong dream come true. It's something I've worked my whole life for, to be in this situation. Realising that got me a little bit choked up."