Tiafoe advanced to the first all-American Grand Slam semi-final since 2005 on Tuesday when Grigor Dimitrov retired injured trailing 6-3, 6-7, 6-3 4-1, just hours after Fritz moved past Alexander Zverev 7-6, 3-6, 6-4, 7-6.
The winner of Friday's clash will become the first American man to reach a Grand Slam final since Andy Roddick lost to Roger Federer at Wimbledon in 2009. Roddick was the last US player to win a men's major when he won in New York in 2003.
Tiafoe, who reached the semis at Flushing Meadows in 2022, said he and Fritz were at opposite ends of the personality spectrum.
"As personalities you can't meet two more extreme," Tiafoe told reporters. "He's video game, never leave the room, goofball. I'm loud, obnoxious at times.
"But he's also very funny. He's got that dry humour, smart ass, but at the same time that's why we like each other because we're so different, and that's why we get along so well."
On the court, there are more similarities than differences.
"Then as competitors, we're very alike, hate to lose. We battle hard, but personalities, we're very different. It's funny to see our relationship how we've gotten older," he added.
"It's going to be epic. Popcorn, do what you got to do. It's going to be a fun one on Friday."
Tiafoe, the 20th seed, comes into the semi-final having won only one of his seven meetings with Fritz but hoped playing at Arthur Ashe Stadium would work in his favour.
"It's different on Ashe," he said. "Obviously you have to learn from those (defeats). A couple of those, I thought I actually should have won.
"I don't think those matches are anywhere near what this match would be, so it's tough to even go from there. Playing quarters of Acapulco and playing semis at Ashe at night, hopefully at night - it's a little different."
The tournament has seen a number of top contenders go out early, while four-time champion Rafa Nadal is absent due to concerns about his fitness, and Tiafoe said men's tennis was much more open in the current era.
"It's not like it once was where you make quarter-finals, you play Rafa, and you're looking at flights," the 26-year-old added. "That's just the reality.
"Now it's just totally different. No one's unbeatable. Especially later in the season where guys are maybe a little bit cooked. Maybe just not as fresh and they're vulnerable."
