Federer had already ruthlessly claimed the first set 6-1 and was cruising 5-2 in the second set, when the Korean made a decision to opt out of the game.
The 21-year-old was joined by his agent Stuart Duguid in the post-match news conference who explained what had happened.
Federer now advances to face Marin Cilic in Sunday's final for a chance at his 20th Grand Slam.
After 1 hour 2 minutes under the closed roof on Rod Laver Arena, he's on par, 7-7 (but still well below his marks at the other majors: 11-1 at Wimbledon, 7-3 at the U.S. Open, and 5-2 at Roland Garros).
In a repeat of last year's Wimbledon final, we should be treated to a more competitive affair this time around as blisters curtailed Cilic's performance significantly at SW19. The Next Gen ATP Finals champion had toppled Novak Djokovic and Alexander Zverev en route to his maiden Grand Slam semi-final, but was unable to bring his best against Federer as blisters took their toll.
It got no better in the second set with Federer again breaking in the fourth game before the trainer was called on to the court to treat Chung for his foot blisters.
"Not having a brutal semi-final, he'll have rest and we'll see a different Marin Cilic this time".
The South Korean confirmed he had been struggling with multiple blisters for several days and an injection to try to numb the pain was not successful. I hope I can start serving well from the get-go, not get into too much trouble early.
"I thought he was an incredible athlete and a very good ball-striker", Godwin said. "It was more for the [spectators] than for me", he joked in his on-court interview after the match. Not under the circumstances I was hoping to or not planning with.
"It's worse than regular blisters. I can't finish the match, so I can't play anymore", he said.
Cilic overcame him on the way to winning the 2014 US Open final, but it is his only win in nine encounters and the Swiss defending champion has glided to the brink of another title without dropping a set. "I think [I took] a lot of confidence".
"I'm just happy I'm in the finals to be honest".
"If I play bad on the court, it's not good for the fans and audience as well", he said.
Ominously, Federer added: "I'm just pleased that actually my game has been good from the very beginning of the tournament so far".
Federer is supremely confident he has it all in place to join Djokovic and Australian Roy Emerson with the most Australian titles. Really honored to play with Roger in semis in Grand Slam. I'm just learning a lot.
"However, I had to make a tough decision given that I can not compete 100% against Roger, in front of many tennis fans".
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