Americans Shelton and Korda fail to reach finals at Australian Open tune-up events
Shelton, who burst onto the scene last year by reaching the Melbourne Park quarter-finals and also got to the US Open semis, was looking to reach his second career final but the world number 16 came unstuck against Taro Daniel (30) at the Auckland Classic.
Daniel, ranked 74th in the world, beat Shelton 7-5, 7-6 to record his fifth victory over a top 20 opponent and the Japanese player will meet Alejandro Tabilo (26) in his first tour final since Istanbul in 2018.
Tabilo beat Arthur Fils (19) 6-2, 7-5 to progress to the final.
"It's always difficult to play against Ben because he doesn't give you much rhythm," Daniel said. "The ball is really alive and it's about who can put on a little more pressure.
"The tie-break was a real dog fight."
At the Adelaide International, world number 32 Jiri Lehecka (22) thumped the 29th-ranked Korda 6-2, 6-1 and will face Jack Draper (22) in the title clash.
Draper, ranked 62nd in the world, had already knocked out top seed Tommy Paul in the quarter-finals, and on Friday the Briton continued his impressive run when he beat Alexander Bublik 7-6, 6-4 to reach the final.
This is the second time Draper has reached an ATP final, after he lost to second seed Adrian Mannarino at the Sofia Open in November.
Former French Open champion Jelena Ostapenko (26) continued to build momentum for the Australian Open, which begins on Sunday, when she defeated Ekaterina Alexandrova (29) 6-2, 7-6 in the semi-finals of the Adelaide women's draw on Friday.
Ostapenko will meet Daria Kasatkina (26) in the final after her semi-final opponent, second seed Jessica Pegula (29), withdrew due to a gastrointestinal illness.
"Unfortunately I woke up not feeling great. Really wish I could have played tonight," Pegula said.
At the Hobart International, the top two seeds will meet in the final after American second seed Emma Navarro (22) beat Yuan Yue (25) of China 6-4, 6-3 in Friday's semi-final and top seed Elise Mertens (28) of Belgium overcame Australia's Daria Saville (29) 6-4, 4-6, 7-5.