Hyeon Chung was understandably heartbroken when he retired injured during his Australian Open semi-final against Roger Federer yesterday.

The world number 58 had never progressed so far in a Grand Slam, which made his decision even more unbearable, but he simply could not continue.

Federer was 6-1 5-2 up anyway, so in all likelihood would've gone on to win had Chung put himself through an almighty pain barrier, but it means the Swiss has the opportunity to win major title number 20 against Marin Cilic tomorrow.

Having dispatched Novak Djokovic in straight sets in round four, Chung would've fancied his chances of another giant-killing, but the 36-year-old just had too much for him.

Remarkably, Federer hasn't dropped a single set during the tournament, as he looks to defend the crown he beat Rafael Nadal to 12 months ago.

While a defeat is naturally disappointing for Chung, he is set to get a huge boost in the ATP rankings thanks to his performances, moving up into the top 30 players in the world.

However, more eyes will be on him in future events, notably because he saw off Djokovic with such ease, and he will have to deal with more pressure.

We would undoubtedly have seen a different game had it not been for such a painful injury, but he had already been carrying it through his last couple of matches, which makes those wins even more impressive.

Just to prove how severe the issue was, Chung uploaded a picture to Instagram after the match, and it is quite horrific.

Judging by that, how he even managed to play is quite remarkable, and it's no wonder he was forced to quit.

Having played so much intense tennis during the Australian Open, more than ever in his career, it isn't surprising that such an injury would surface, but that is at the extreme end of the scale without any question.

The adrenaline of his first semi-final probably helped at the start, but as a defeat seemed more and more likely, it must have been excruciating for the South Korean, with the blister taking up a decent proportion of his foot.

To put up with something as gruesome as that shows how much fight and potential Chung has though, and Federer himself seems to think he can go a long way in the game with that mentality.

"I think he’s going to have a lot of success," the Swiss started. "At what stage, how much, we will see.

"I did see today why he beat the players like Novak, Sascha [Zverev], other players in the past. He’s very steady mentally. Today I’m sure he was having a lot of pain with his feet. Otherwise, why would you retire in such a big-match situation.

"And you couldn’t tell almost. I like that about the idea of hiding any problems from the opponent. That was very impressive, to be honest.

"Then just the way he plays tennis, his forehand and backhand. I know what he was capable to do against Novak in terms of defense, although today he couldn’t show it. It’s very impressive. I think it’s going to give him a lot of possibilities moving forward. The question is with that kind of a game, you just got to take care of your body, also the schedule maybe.

"It’s very intense, his tennis. I wish him the best. I was very impressed."

Chung will be hoping that the injury doesn't flare up at the French Open in May, where he will undoubtedly be looking to continue the Grand Slam form he has shown in Melbourne.

There will just be the small matter of 10-time champion Rafael Nadal in his way then.