Stefanos Tsitsipas booked his place in the quarterfinals of the 2019 Australian Open on Sunday after ralling to beat No. 3 seed Roger Federer, 6-7, 7-6, 7-5, 7-6. Here are five of the Greek 20-year-old's best answers from his post-match pres conference. 

Q: I remember you saying at Wimbledon you'd been watching the [Roger] Federer-[Pete] Sampras match. Is that a match you watch every slam or by surface? Have you been watching that match here as well?

Stefanos Tsitsipas: I haven't watched that match here in Melbourne yet. Actually, that was fourth round, as well. That's crazy. What a coincidence.

Yeah, I did watch that match when I was playing Wimbledon, grass courts. I did watch couple of his matches in the past that he played on hard courts. I watched few highlights of him on the best possible platform: YouTube. It's the platform, I'm not paid to say it, that I used to do the analyzing, as you said.

Yeah, I kind of watch some highlights of players that beat him in Grand Slams. It was actually not Rafa, Djokovic, but some other players that have beaten him in the past US Open. Very similar game style like me. I will not say which player. He did beat him in US Open a few years ago.

It was a good example to see the way he played, the way he fought into the match to get that win. I'm pretty sure that helped today.

Q: I understand you spent some time with Andy Murray at a training camp. Could you tell us what you gained from that, the effect it might have had on your development as a tennis player.

Stefanos Tsitsipas: I have practiced with him three or four times in the past. That was many years ago. That was two years ago. I don't know if that's considered 'many'. I did practice with him.

He got invited to the Mouratoglou Tennis Academy, my training base. We had a couple of hits with him during that week. I learned a lot. I learned that you need to be a hard worker to make it big because he did stay in the court during all of our practice sessions more than three hours. He would work on many things. That was inspiring to see.

The way he worked, the way he developed as a player, even though at that time he was top five, if I'm not wrong. That definitely helped me a little bit to understand, to get a better taste and understanding of what's going on in that level of tennis.

I think for sure it had an impact on me.

Q: What does this triumph mean to you?
Stefanos Tsitsipas: A flashback of, I don't know, just happiness, pure happiness. It was a very emotional moment. It was somethin- ag,beginning of something really big. I felt joy. I felt happiness. I felt a huge relief going out of my shoulders.

That moment is definitely something that I will never, ever, ever forget. This match point is going to stay, I'm pretty much sure, forever, for the rest of my life.

Q: Do you believe this match is the changing of the guard?
Stefanos Tsitsipas: I mean, I try to take every match differently. For sure it's a good win against Roger. I mean, we all know who Roger Federer is, what he has done in tennis. But I still have to keep my focus, keep my concentration on further goals that I want to achieve. That's a very good beginning. I need to stay humble.

This win is a good milestone, let's say good first step, as I said, to something bigger. I do feel like my game is pretty good at the moment. I feel confident. That's very important. I'm really pumped and excited to be competing in the quarterfinals two days from now. I'm really waiting for that moment.

Q: How do you plan to go back to square one? What is your perspective on the remainder of the tournament? Can you go all the way?
Stefanos Tsitsipas: For sure. That's why I'm here. That's why I'm playing, for the trophy, for the title. Yeah, again, I feel good. I really want it badly. I really want to proceed further in the tournament, yeah, to make myself happy and the people that are cheering for me happy.

I really like this atmosphere that's on the court, the whole dynamic of it, I would say. It just feels so nice to be playing on these courts. It's spectacular. I really want to stay here as long as possible. That's my goal.