| 26 Jan 2018, 00:00 | Update : 26 Jan 2018, 20:47
Roger Federer made it through to a record seventh Australian Open final when South Korean Hyeon Chung retired in the second set of their semi-final.
The Swiss led 6-1, 5-2 when 21-year-old Chung was forced to call it quits, three games after being treated for a blister on his left foot.
Defending champion Federer, 36, goes on to face Croatian sixth seed Marin Cilic in Sunday's final.
The world number two is seeking a sixth Australian and 20th Grand Slam title.
Federer was on course to take a two-set lead after just 62 minutes when the second semi-final came to an abrupt halt.
Chung's management later said the problem had developed during the tournament, and they had tried to ease the pain with injections as it was much worse than a regular blister.
‘I thought the first set was normal,’ said Federer. ‘I couldn't tell what was going on with my opponent.’
‘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,’ said Federer.
Chung had spent around 12 hours on court heading into the semi-final, including a grueling win over Novak Djokovic in round four, and the physical effort finally took its toll.