American world number 15 Ben Shelton came from a set down on Saturday to beat Argentine Francisco Cerundolo and reach the final of the Munich ATP event.
Shelton won 2-6, 7-6 (9/7), 6-4 and will face the winner of the other semi-final between world number three Alexander Zverev and Hungary's Fabian Marozsan in Sunday's final
Outclassed in the opening set, the 22-year-old American's fightback began in the second with an early break.
Cerundolo, ranked 22 in the world, fought back, taking the set to a tiebreak, which Shelton won 9-7.
Cerundolo broke in he first game of the third but Shelton broke back at once and broke again in the last game to take the match in two hours and eight minutes and reach the fourth ATP final of his career.
Shelton said after the match he was still working to improve on clay.
"Not everything is straightforward and perfect on the clay. You're gonna get broken more... but you can also break more," Shelton said after the match.
"I think dealing with adversity and adapting makes a great clay-court player. I'm trying to learn day by day."
Home favourite Zverev, who celebrates his 28th birthday on Sunday, is bidding to win his third Munich crown, having lifted the title in 2017 and 2018.