WATCH the ATP Tour LIVE in Australia on beIN SPORTS | Subscribe here and take advantage of our 7-day FREE TRIAL

The No.5 seed from the United States is the first American into the showpiece match at the finals since James Blake in 2006, and it will be Fritz's fifth final of an impressive season on the ATP Tour.

"I felt like I played an almost perfect first set, but things can change so quickly when you're playing someone like Sascha [Zverev]," Fritz said.

"I found myself in some tough spots in the third [set], when we both started to get on each other's serves even more.

"When I was trying to be aggressive I didn't feel like it was doing much. I just told myself at the end that I had to fight and be solid and tried to take care of my serve the best I could and give him absolutely nothing from the back.

"I trust my game and I trust my level. I don't feel anywhere near as uncomfortable in these situations anymore because I've been putting myself in these situations against the top guys at big events a lot lately.

"I'm really confident in my game."

Fritz, who won at Delray Beach and Eastbourne this season, moved up one spot to No.4 on the world rankings as a result of the win, again emulating Blake, who was the most recent American to finish inside the top five at the end of a season in 2006.

The victory was far from easy, but Fritz became the first player to break Zverev's serve this week when he went 4-2 up in the first set and held the break to claim the set.

The German fought back in the second, though, holding off another break point against him after having taken a service game off Fritz to level matters at a set apiece and set up a thrilling final stanza.

Fritz fought back from 0-40 down to hold serve at 2-2 and Zverev saved three break points at 3-4 as the pair went toe-to-toe, playing out a 10-minute game at 5-5 in which Fritz was again forced to save a break point to hold at 6-5, Zverev holding too to force the tie-break.

Errors crept in for Zverev to put Fritz in the driving seat, and with his first match point he claimed the win, ending an absolutely epic encounter and moving himself into the title decider, where he will face Jannik Sinner or Casper Ruud.