The hugely experienced Swiss ace is an overwhelming favourite as he targets a 20th Grand Slam title, but the unseeded 21-year-old has already sent Novak Djokovic packing, proving anything can happen.
Cilic is already through to his first ever decider at Melbourne Park after sweeping past Britain’s Kyle Edmund in three comfortable sets in his semi-final on Thursday.
Simona Halep and Caroline Wozniacki will face off for the women’s crown on Saturday in a clash that will also determine the world number one ranking.
Defending champion Federer is playing a record 14th semi in Australia and aged 36 shows no sign of surrendering his long invincibility, with a record 30th Grand Slam final beckoning.
He is the oldest man to reach the last four here since Ken Rosewall (42 years) in 1977.
Federer admitted he knew little about Chung and needed to do some homework, but was wary after he upset Djokovic.
“I’m very excited to play Chung. I thought he played an incredible match against Novak,” he said ahead of their evening showdown on Rod Laver Arena.
“I mean, to beat him here is one of the tough things to do in our sport, I believe.”
It has been a breakthrough tournament for Chung, whose 58th ranking is expected to tumble after toppling not just six-time champion Djokovic but world No.4 Alexander Zverev.
He is the first South Korean to reach the last four at a Grand Slam and excited at the prospect of playing Federer, who is yet to drop a set.
“I’m just trying to play the same all the time. I’m just trying to fight 100 percent,” he said.
If Federer, who is chasing a sixth Australian title, gets through, he will fancy his chances against Cilic. He holds an 8-1 record against the Croat, including victory in the 2017 Wimbledon final.
Cilic has beaten Chung on all three occasions they have played, most recently in Brisbane in 2016.
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