MELBOURNE — It wasn’t how Roger Federer expected to advance.
The Australian Open’s defending champion was leading, 6-1, 5-2, when Hyeon Chung retired in the second set of their semifinal Friday night. Federer is within one win of his 20th Grand Slam singles title.
“You do take the faster matches whenever you can because there’s enough wear and tear on the body,’’ he said. ‘‘The thought process is not like ‘What would have been better?’
‘‘That’s why this one feels bittersweet. I’m incredibly happy to be in the finals, but not like this.’’
The final will be Federer’s record seventh at the Australian Open and 30th at a Grand Slam event.
Chung tried everything to disguise the pain of the raw patches on his left foot which, his agent explained, were ‘‘blisters under blisters under blisters.’’
Federer knows the feeling. He also sensed something wrong with Chung’s movement.
‘‘I’ve played with blisters in the past a lot, and it hurts a lot. And at one point, it’s just too much and you can’t take it anymore — you can’t go on,’’ he said. ‘‘He’s played such a wonderful tournament, so credit to him for playing so hard again today.’’
Federer’s well poised for Sunday’s match against Marin Cilic, who has had an extra day of rest, but Federer was hardly taxed. His match lasted 1 hour and 2 minutes under the closed roof.
Cilic was hampered by blisters when he lost to Federer in last year’s Wimbledon final, but he has made a relatively pain-free run through the other half of the draw, including a quarterfinal win over an injured Rafael Nadal.
Even if Chung had been fit, he was trying to reach his first ATP final against a player who has won 95 titles.
Chung had an incredible run at Melbourne Park, becoming the first Korean to reach a semifinal at a tennis major and attracting plenty of attention for beating No. 4-seeded Alexander Zverev in the third round and six-time Australian Open champion Novak Djokovic in the fourth.
But it took a toll. He needed a pain-killing injection before the match, and a medical timeout to re-tape his left foot after going down a break in the second set. He played only two more games before he quit.
‘‘I did right thing. If I play bad on the court, it’s not good for the fans and audience as well,’’ he said. ‘‘I really hurt. I can’t walk no more.’’
The 36-year-old Federer predicted a bright future for Chung, 15 years younger. Chung also believed the experience will prepare him better for the rigors of best-of-five-set tennis at Grand Slams.
‘‘For sure. I play really good in [the] last two weeks. I make first round 16, quarters, and semis — I play [Zverev], Novak, Roger,’’ he said. ‘‘I can play better and better in the future.’’
With victory, Federer ensured one of the so-called Big Four — with Nadal, Djokovic, Andy Murray — has featured in the final since 2005. Stan Wawrinka’s win over Nadal in 2014 was the only final since 2008 that didn’t feature two of the Big Four.