"It was such a tough match, it's not often you see three set tiebreakers," said the American after her third consecutive three-set encounter in the tournament. "She played a really tough match and it could have honestly gone either way.
"I'm super excited to make it to my sixth final."
Watch tennis live on Eurosport and the Eurosport Player
US Open
Who's playing the 2021 US Open and who is missing?
23/08/2021 AT 21:34
Kenin, 21, was not at her best and it was Van Uytvanck who had more winners and fewer unforced errors, but it was the American who held her nerve in the decisive tiebreak to advance.
Van Uytvanck looked to finish points quickly and also won more points at the net but Kenin prevailed when she was able to extend rallies, firing a few well-placed passing shots when the Belgian advanced to the net.
Earlier, the unseeded Friedsam beat seventh-seeded Russian Daria Kasatkina 6-3 3-6 6-2 in a little over two hours to reach her second career final -- her first since 2015 before injuries saw her fall outside the top 350 in the singles rankings.
Friedsam, 26, converted five of 11 break points while Kasatkina was let down by six double faults.
US Open
Nadal becomes latest big name to withdraw from US Open due to foot injury
20/08/2021 AT 10:30
US Open
US Open 2021 - All you need to know ahead of season's final Grand Slam
12/08/2021 AT 12:27