Melbourne, Jan 26 Defending champion Roger Federer on Friday reached the final of the Australian Open after South Korea's Hyeon Chung quit in pain trailing 1-6, 2-5. World No.56 Chung, the first South Korean to advance into the singles semi-finals of a Grand Slam tournament, pulled the plug after feeling pain in his left foot, reports Efe. "It's bittersweet to reach the final this way," said 36-year-old Federer, the oldest man to march into an Australian open final since 1972. It will be his seventh final at Melbourne. The 19-time Grand Slam champion, who fired nine aces and 24 winners, has not yet dropped a set at this year's Australian Open. In his 30th Grand Slam final, Federer is due to play Croatia's Marin Cilic, who eliminated Britain's Britain's Kyle Edmund 6-2, 7-6 (7-4), 6-2. Cilic also defeated world No. 1 Rafael Nadal in the quarter-finals 3-6, 6-3, 6-7 (5-7), 6-2, 2-0 after the Spaniard retired injured. "We saw it against Rafa, and we saw it again last night against Edmund. He (Cilic) brings power, basically everything. He had the same problem as Chung had in the Wimbledon final. We will see a fresh and ready Marin this time around," added Federer, who beat Cilic in last summer's Wimbledon final. Chung told Xinhua news agency: "Over the last few days I've had blister, over blister, over blister. I had it shaved off and now it is red raw. "We tried an injection to numb the pain but it didn't work. A lot of players get callus and as they go, they shave them down, but because I played so many matches in a row, I didn't know to shave them down, so that's how they started."