Jannik Sinner has his first ATP Finals crown firmly in his sights after crushing Casper Ruud 6-1, 6-2 on Saturday to set up a title decider with Taylor Fritz, the man he beat to win the US Open two months ago.

Roared on by a partisan home crowd in Turin, Sinner extended his winning streak to 10 matches with another dominating display which showed why he is the first Italian to top the ATP's end-of-season world rankings.

The 23-year-old has reacted to losing last year's final to Novak Djokovic by displacing the Serbian tennis icon at the top of the game, winning seven tournaments this season including his debut Grand Slam victory at the Australian Open before triumphing in New York in September.

Sinner barely gave Ruud time to breathe as he rattled off the first three games and took the first set in half an hour, before sweeping to a comprehensive victory.

"It's a great, great feeling. It's really special playing here," said Sinner.

"It's a really important tournament, last year we lost the final, this year we've got a chance to try again and do better than we did last season.

"But regardless of how it goes tomorrow it's been an emotional week with some great moments."

Ruud, who hadn't played Sinner for three years before Saturday, compared the shots he faced to "rockets" and was struck by how much he has improved.

"You feel like unless you hit a ball with really good depth or close to the sidelines, and even if you hit close to the sidelines but not fast enough, he's going to rip it back at you," Ruud told reporters.

"I got to practice with him here earlier leading up to the tournament. He also kicked my ass there. In a way I knew what I was facing today."

- Fritz's revenge chance -

Fritz has a task on his hands to become the first American Finals winner since Pete Sampras 25 years ago as he has been comfortably beaten both times he has faced Sinner this year, with straight sets victories in the US Open final and the group stage in Turin.

The world number five is the first US man to make the final since James Blake in 2006 after a thrilling 6-3, 3-6, 7-6 (7/3) triumph over Zverev.

Fritz has a chance for revenge on Sinner for the US Open final defeat, following a gruelling match in northern Italy.

Both players had chances to take control in a topsy-turvy third set, but failed to capitalise on a host of break points before Fritz held his nerve better in the tie-break to claim a spot in the final.

Fritz managed to save three break points in game five of the third set, just when it looked like Zverev was set to take control of the match.

"That was probably the biggest turning point, I lose one of those points and that's probably it. That's kind of how it goes with playing Sascha," said Fritz, who got to the semis two years ago.

Zverev was aiming for a tour-leading 70th win of the season but his winning streak was snapped at eight matches after coming into Saturday's clash having not dropped a single set or service game in Turin.

The 27-year-old admitted that he failed to take his chances when it counted after playing arguably the better tennis in the closing two sets of the match.

"It was one of those days where everything, it takes times to get going," said Zverev.

"It's like it's not a natural flow to movement patterns, to your shots as well, to just how you wake up in the morning. Everything is a little bit more tiring. I felt that way today."

On Friday night Zverev described the men's tennis calendar as "crazy", saying that he had not spent more than three consecutive days at home all year.