Roger Federer fought back from losing the first set to beat Marton Fucsovics 4-6 6-1 6-2 6-2 and set up an Australian Open quarter-final against Tennys Sandgren. Federer outlasted John Millman in a Friday night five-setter that the word 'epic' barely did justice, with the 20-time Grand Slam winner down 8-4 in a super tiebreak before reeling off six successive points to win the match at way past midnight. The exertion required in that effort appeared to show in the first set against Fucsovics as Federer was broken, fatally, once, to lose 6-4 and give himself another battle to keep him in the tournament. Sensing trouble, Federer broke early in the second set and enforced his new-found superiority to take it 6-1 in under half an hour. His opponent, ranked 67 in the world, then fell apart completely in the third as Federer raced out to a 4-0 advantage. Fucsovics found some resistance but could not stop Federer taking the set 6-2, and the punishment continued in the fourth as Federer broke early on. Fucsovics survived two more break points to get to 3-2, but he couldn't resist Federer and was broken again as the Swiss great won it 6-2. Federer faces world No. 100 Tennys Sandgren in the last eight after he defeated Fabio Fognini in a fiery encounter on Sunday. Speaking in his on-court interview with John McEnroe, Federer admitted it took him some time to get into the match following his epic against Millman. "The morning after the John match, and this morning, I lay in bed for an hour, I was like, 'when are we going to stand up? One, two, three…!' That's almost how it felt. "I'm good, I was able to recover and play a good match so I'm sure that I'm going to feel better every day that goes by after that match, that's for sure." On his quarter-final opponent, Federer said: "He was never going to be a baseball player with that name. I'm looking forward to playing him. I've played a lot of tennis in my career but I've never played a Tennys!"