German star Alexander Zverev gets a third chance on Sunday to win his first ATP tournament on grass after reaching the Stuttgart final with a 7-6(8), 7-6(1) victory over American Brian Shelton.

Zverev, who has reached the finals of the other three Grand Slams but never even got as far as the quarter-finals at Wimbledon, will face big-serving American Taylor Fritz.

Fritz, who does have a grass court pedigree having won three of his eight ATP titles on the surface, beat Felix Auger-Aliassime 6-4, 7-6(5) earlier on Saturday to reach his first final this year.

Zverev, 27, was never under pressure on his serve, offering up no break points, but the top seed fell short when he had two chances to break third-seeded Shelton.

His laxness carried on in the first set tie-break when he let slip three set points at 6-3, though, he pulled himself together and prevailed 10-8.

He learned from the first set as he romped through the second set tie-break to win in just over two hours.

"It is my first final on grass since 2017," said Zverev, referring to the Halle final where he lost to Roger Federer.

"I like to play on this surface.

"It will be a huge tussle against Taylor tomorrow (Sunday)."

Earlier in a match of big servers, Auger-Aliassime edged Fritz 15-12 on aces, but the 24-year-old Canadian cracked at the worst possible moment in the first set, losing his serve with the American leading 5-4.

Fritz wrapped up the match in a hard-fought second-set tie-break.

The tournament serves as a warm-up for Wimbledon, where Fritz, even though his game is suited to grass, has never done better than the quarter-finals.