Federer will play Chung after beating Tomas Berdych 7-6 (7/1) 6-3 6-4 while Edmund takes on Marin Cilic.

"I think it’s a good thing," said Federer. "They’ve got to make a move. I find it disappointing when their breakthroughs come at 27, because then we know them for seven years. I like it when we don’t know the guys.

"I hardly know Chung. I’ve hardly spoken to him. I had one Nike appearance once with Edmund over in London. That’s about it. Maybe otherwise I’ve shaken his hand twice and spoken a few words to him."

It is likely to be a taste of things to come, with the old guard beginning to struggle badly with injuries - Federer aside - and the grand slams reverting to 16 seeds instead of 32 from next season.

Federer said: "I think next year when we’ll have 16 seeds, it’s going to be quite different. That’s how I grew up with it. It’s nice to go back to that.

"I do believe in some ways it’s going to open some draws, but at the same time it’s going to be some really tough ones from the get-go, which I think is a good thing. Those first weeks sometimes have become really dull."

Chung became the first Korean player to reach the last eight of a slam by beating an ailing Novak Djokovic and he followed that up by showing his class against Sandgren, an even more unlikely quarter-finalist.

"I’m very excited to play Chung," said Federer. "I thought he played an incredible match against Novak. To beat him here is one of the tough things to do in our sport. I know that Novak maybe wasn’t at 110 per cent, but he was all right. To close it out, that was mighty impressive.

"I think it’s an interesting match for me. I’ll definitely have to look into how I need to play against him because he has some great qualities, especially defensively, like Novak has."

Federer has also followed the progress of Edmund with interest, and said: "It’s a good situation to be in. He can hit freely now. No expectations whatsoever.

"He’ll maybe never be in this position ever again, to have so little expectations. First time in the semis, you’re like, ’I’m going to tear this place into pieces, I’ve got incredible power right now’. Great, great effort. I’m very happy for him."

Federer’s record of not having dropped a set this tournament was threatened by Berdych, who opened up a 3-0 lead and served for the opening set.

Federer got himself fired up arguing with the umpire over a HawkEye review that could not be shown on the screen because of a technical fault and saved two set points before turning the match around.

He revealed afterwards that he sent a message to great rival Rafael Nadal following his withdrawal on Tuesday and that the fate of his fellow top seeds had made him anxious.

"I was actually very nervous going into this match tonight, and that’s why I struggled very early on," he said. "I knew the danger of Berdych. Seeing what has happened to so many other top seeds here in the draw, I was a bit wary."