The world No 2 will now go for his 20th major title on Sunday in the final against Marin Cilic
Roger Federer through to Australian Open final as Hyeon Chung retires injured
Roger Federer has reached the final of the Australian Open after opponent Chung Hyeon retired hurt in the second set of the semi-final.
Federer was leading 6-1, 5-2 at the time when the South Korean chose to shake hands with the world No 2 as he struggled with blisters on his feet.
Federer will now go for his 20th grand slam title on Sunday in Melbourne against Croatian Marin Cilic, the man he beat at Wimbledon in July to win his 19th major.
The 36 year old had sympathy for his unseeded opponent, who had been one of the surprise packages of the tournament as he knocked out six-time champion Novak Djokovic in the fourth round.
I thought the first set was normal. I couldn't tell what was going on with my opponent," Federer said in his courtside interview.
"In the second set I felt he was getting slower. He's had a problem with the blister. It hurts - a lot. At some point it's too much and you make things worse.
"Clearly I'm happy to be in the final but not like this. He's had such a wonderful tournament."
Federer is bidding to retain his Australian Open crown and win the tournament for a record-equalling sixth time to go with his successes in 2004, 2006, 2007, 2010 and last year.