He may have won the 20th Grand Slam of his career in Melbourne on Sunday, but Roger Federer has disclosed that despite all his past success, he still suffered from pre-match nerves ahead of the Australian Open final.

The Swiss great, 36, beat Marin Cilic in five sets under the roof at the Rod Laver Arena in a scorching Melbourne to become only the fourth player of all time to win over 20 Grand Slam titles.

The match itself was a stern test for Federer, as he struggled to shake off Cilic, with the Croat twice coming from behind in sets and winning five games in a row heading into the decider.

But, speaking after he persevered, Federer expressed that he had doubts about his ability to win yet another final.

Federer is accustomed to meeting the likes of Rafael Nadal, Novak Djokovic, and/or Andy Murray in the latter stages of the biggest tournaments, so arguably felt undercooked going into the final having not dropped a set.

Even during his semi-final against Chung Hyeon, who surprised many to reach the latter stages of the tournament, Federer was given a smooth passage to the final after his opponent retired in the second set.

Something he said hindered him, instead of helping him.

"Today for the finals, I didn't fall asleep very well after the Chung match. I think it surprised me that at this stage of a competition in semis, to get a walkover, that was very odd for me.

"I couldn't fall asleep until about 3 in the morning. All of the next day I was already thinking about how should I play Marin, how cool would it be to win 20, but no, don't think of it, but how horrible would it be to lose it.

"I had it for over 36 hours, to be honest. It was a lot. I felt like the finals came very quickly because of not dropping any sets and stuff, still having so many emotions left. I needed to probably work through these emotions this way."

And, Federer also admitted that the nerves were not just about the prospect of winning the final, which would give him the magical figure of 20 Grand Slams, but also came earlier in the tournament.

"You can't explain it sometimes," he said.

"It is just a feeling you get. It's like against Berdych, I felt, like, I'm probably going to lose this one. I was not negative, but I just felt like I saw a loss was coming somehow.

"Not because I was not feeling good or anything, I just felt like maybe Berdych is really feeling it."

Despite still experiencing nerves before important matches, Federer's form would suggest he is not being influenced by them, having won three out of the four last Grand Slams and experiencing another purple patch of form in his illustrious career.