Veteran Tommy Haas beat John Isner 6-3 6-4 to book his place in the final of the SAP Open in San Jose.
The 34-year-old from Germany earned his 25th career final after benefiting from a lacklustre performance from the usually-dominant serving of Isner.
The American was successful on just 58 percent of his first serves on his return from a knee injury.
"Normally I can serve better than how I did," Isner said. "That's what decided the match. He played a lot better than I did. He didn't miss too many serves. He was very good."
Haas, who first played in San Jose in 1998, will take on top seed Milos Raonic in the final after the Canadian saw off another big-serving American Sam Querrey 6-4 6-2.
Raonic will attempt to become the first player in the Open era to win in San Jose three times in succession after hitting 12 aces against Querrey.
"I've been going up and down in regards to my return," he said. "I started aggressively and carried that through the match. I'm returning well, moving well and serving well, the whole thing.
"Everything is on the right track and that gives you confidence that all the work is paying off."