Switzerland’s Roger Federer serves to Hyeon Chung of South Korea in their Australian Open semi-final in Melbourne on Friday. Federer was ahead 6-1, 5-2 when Chung pulled out with toe blisters. (Photo: AP)

Melbourne: Defending champion Roger Federer eased into his seventh Australian Open final in a bitter-sweet win after South Korean young gun Chung Hyeon retired injured in their last four showdown on Friday.

The Swiss great was leading 6-1, 5-2 when Chung called it quits with foot blisters, and he will now face Marin Cilic in his 30th Grand Slam final on Sunday.

Chung, the first South Korean man or woman to play in a semi-final at one of the four majors, was treated in a medical timeout for the left foot problem just two games earlier.

But it came as a big surprise when the 21-year-old walked to the net at 30-30 and trailing 2-5 after 62 minutes in the second set to throw in the towel.

It pitched Federer into his seventh Australian final as he chases his sixth Melbourne title and a record 20th Grand Slam victory.

He leads 2014 US Open champion Cilic 8-1 in their meetings.

“This feels bitter-sweet. Obviously I’m incredibly happy to be in the finals, but not like this,” Federer said of the abrupt ending.

“I would have preferred a normal end, yes. But I must admit, as well, you do take the faster matches whenever you can.

“There’s enough wear and tear on the body, there’s enough tough matches throughout the season that when they happen, you take them.

“There’s nothing you can do anyway about it. I’m just happy I’m in the final, to be honest.”

The Swiss maestro now has a 30-13 win-loss record in Grand Slam semi-finals and has yet to drop a set in this year’s Australian Open.

Federer broke Chu-ng’s opening service and twice more to romp away with the first set in just 33 minutes as the Korean made a flurry of errors.

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. Chung only lasted a bit more than two games before pulling out to a stunned silence.

Federer broke Chung’s serve four times off 11 break points and only had one break point on his own service.

The Swiss second seed hit 24 winners while Chung made 17 unforced errors in 14 games, eight of them off his normally pot-ent forehand, which Federer targeted.

High stakes in women’s final

Simona Halep and Caroline Wozniacki will compete for high stakes in Saturday’s final, having each needed to save match points to prevent a premature exit at Melbourne Park.

The winner at Rod Laver Arena is not only guaranteed a long-awaited maiden grand slam title but also the world number one ranking in the game of thrones that women’s tennis has become in Serena Williams’s absence.

The final will be the first between two non-slam winners in 38 years, since Hana Mandlikova beat home favourite Wendy Turnbull in 1980. But in a fortnight where the seeds have been scattered to the wind, Halep and Wozniacki may both feel fortunate to still be in the hunt.   

Results

Men’s singles semi-final: Roger Federer (SUI x2) bt Chung Hyeon (KOR) 6-1, 5-2 ret.
Women’s doubles final: Timea Babos (HUN)/Kristina Mladenovic (FRA x5) bt Ekaterina Makarova/Elena Vesnina (RUS x2)
6-4, 6-3.