World number seven Fritz fought back to defeat 53rd-ranked Korda 6-7 (2), 6-4, 7-6 (5) and book a place against Croatian Marin Cilic, the 2014 US Open winner, in a Saturday semi-final.
Fritz, now 4-1 in matches against Korda, fired 22 aces and won all four break points he faced to conclude matters in two hours and 30 minutes.
"Just (proud of) the way I handled those big moments in that match," Fritz said. "He was constantly putting a lot of pressure on my serve. He was playing really well."
Fritz also fought back after suffering a right elbow injury returning a Korda shot in the second set.
"I just instantly got this really sharp pain in my elbow, served one serve afterwards - luckily I made it - and knew right then I needed to get the physio there. It was pretty bad," Fritz said.
"I had a couple games where I was really scared to snap my serve because I feel that pain I'm going to lose that point, but then I got some painkillers, I started to feel better and then I started to just trust it and it wasn't even something I was thinking of most of the second and the full third (sets)."
Up 5-4 in the final tiebreaker, Korda sent two forehands long and Fritz blasted a service winner on the final point for the triumph.
Cilic advanced by beating British qualifier Jack Pinnington Jones 6-1, 6-4.
Fritz is 2-1 in ATP play against 37-year-old Cilic, winning on Monte Carlo clay in 2022 and at Indian Wells in 2017 but losing a 2021 final at St. Petersburg.
Canada's Denis Shapovalov kept his title defence on track, beating third-seeded Alejandro Davidovich Fokina of Spain 5-7, 6-4, 6-3.
Shapovalov next faces second-seeded American Ben Shelton, who rallied for a 5-7, 6-3, 6-4 victory over Serbian Miomir Kecmanovic.