Stefanos Tsitsipas and Alexander Zverev will duel for the ATP title in Acapulco, the top two seeds advancing with straight-set semi-final wins on Friday.
World number five Tsitsipas of Greece beat Italian qualifier Lorenzo Musetti 6-1, 6-3 to reach his first final of 2021.
Zverev was shaken but not unnerved by an earthquake in the second set of his 6-4, 7-6 (7/5) victory over fellow German Dominik Koepfer.
"The lights started shaking and the crowd felt it more than we did," Zverev said of the 5.7 magnitude quake with an epicenter 60 km away in San Marcos.
"We were running around the court, so we had to play a point during the earthquake," he added. "We didn't feel much, but still, obviously, I know it happens here in Acapulco."
Koepfer, unfazed, seized the first break of the second set to take a 3-1 lead.
But Zverev, ranked seventh in the world, kept the pressure on, creating break chances in each of Koepfer's next three service games and converting at 5-4 for a break that would force the tiebreaker.
Zverev will be seeking a 14th ATP title and his first of the year when he takes on Tsitsipas, a five-time ATP title winner who was playing in his third semi-final of the year after making the final four at the Australian Open and Rotterdam.
"I am really looking forward to the final," said Tsitsipas, who has won five of six prior encounters with the German. "Sascha is someone I've played against in the past and it's never easy. We're both really hungry and we're both very competitive."
Tsitsipas needed just 79 minutes to end the run of 120th-ranked Musetti, the world No. 120 who had reached his second career semi-final in just his fourth ATP main draw appearance.
He stormed through the first set, but didn't get a break chance in the second until the seventh game, when he broke his 19-year-old Italian opponent at love.
Serving to stay in the match two games later, Musetti fended off three break points before Tsitsipas finally collected the win when the Italian hit a backhand into the net.
"We'll definitely see a lot from Lorenzo in the future, he has a wonderful one handed backhand and creates lots of opportunities," Tsitsipas said. "He showed his level this week."