Q. We saw you angry in some parts of the match. I don't know whether that anger was due to crowd supporting Bautista Agut or you were angry at your opponent or at yourself?
NOVAK DJOKOVIC: Why would I be angry at Bautista Agut? He's playing great tennis. He's focused. He deserves to win the second set.
I was upset with myself. I was frustrated with the fact from 4-2 and 15-40 I wasn't able to capitalize on those opportunities and to lose five games in a row. I cannot allow myself to do that. It happens. I'm a player that shows emotions.
Obviously at that moment it wasn't easy, but I managed to kind of regroup and use the experience of facing these particular situations before in my life, knowing what to do next.
So important thing is that I managed to find a way to win.
Q. How do you find that sometimes letting out a little bit of whatever is going on in there helps you after?
NOVAK DJOKOVIC: I mean, sometimes goes in your favor, sometimes against you. Everybody's different.
I'm not saying that this is a proper way to do, to express your emotions. Sometimes you're not proud of what you do. But, again, important thing is to be aware of what you did and to kind of bounce back and gather the concentration.
Atmosphere was electric, as it always is in night session in Arthur Ashe. Crowd got into it the end of the second set when he broke me. Then we had a match. We definitely had a match.
As I said, should have done better 4-2 second set, but credit to him for fighting, for making me work. It was a very physical match. I played over three hours, and just glad that I managed to stay tough.
Q. Earlier today the Williams sisters both reached the quarterfinals to face each other. When you think about their rivalry and these two sisters stepping on the court to face one another, what goes through your mind?
NOVAK DJOKOVIC: The first thing that comes to my mind is how would I feel to play my brother, and I don't think that would be possible, honestly.
I in a way admire what they're doing for so many years to play against each other on such a big stage.
It's strange, you know. They are sisters. They live together. They grew up together playing tennis. Of course they love each other, but then very have to be professional and go out on the court and play each other so many times in the finals of Grand Slams, in the biggest matches.
They both were No. 1's of the world.
Chapeau for that. But I don't know if I'll be able to play my brother. It's not possible. I would not be able to handle on the court.
Q. What do you think it says about them that they've been able to do this for so long and battle each other for so long?
NOVAK DJOKOVIC: Yeah, as I said, it's admiration. But for me, somebody who has siblings, it's hard to watch, honestly, as well. It's just going after each other and after that going back to the same home like nothing happened.
So that's a really tough one.
Q. Did he raise his level in the end of the second set or did your level drop?
NOVAK DJOKOVIC: Well, I think both. I started allowing him to control the rallies. I didn't do what I did for set and a half, which was after few balls stepping in and taking control.
If you give him an opportunity, if you drop your level, he's a kind of a player, similar to David Ferrer, that is going to get on top of you, which he did.
Q. You mentioned there were no easy points. Is it good sometimes to have a tough test like this before the crunch end of the second week?
NOVAK DJOKOVIC: It's always good to have a test like this in a Grand Slam. You know, better earlier than later.
But, again, it's hard to predict how the matches are going to look like. As you progress in the tournament the matches are getting tougher, which is logical to expect.
I'm going to play Feliciano López now who is also Spanish tennis player but doesn't possess the typical Spanish style, back of the court.
He comes in and slices; he is physically very strong; big serve. Hopefully I can be ready for that one.
Q. Serena was talking how this year all the crowd is pulling for her to get this Grand Slam, because she's used to having the crowd wanting the underdog to win. You've almost never been an underdog. Does that get tough having the crowd always wanting to have a competitive match?
NOVAK DJOKOVIC: It depends. It really depends. I understand also the crowd that likes to support the underdog. They want to see a good match.
But, you know, it's on you to focus on the support that you have. At the end of the day you're alone on the court. You got to do your job regardless of who is cheering you on or not.
Q. You haven't lost before the quarterfinals of a Grand Slam since the French Open 2009. Does that seem crazy to you?
NOVAK DJOKOVIC: Well, I'm proud of the fact that I've been able to achieve so much in my career so far and to be able to play my best on the Grand Slams, which I was always aiming for.
I'm always trying to set up my form, shape, for these events. This is where I want to peak. These are the tournaments that matter the most.
I've been able to play consistently well throughout the years and been fortunate to win nine Grand Slams.
I keep on going as long as there's this flair in me.
Q. You've been No. 1 for quite some time now and you know what it takes to get there and stay there. How impressive is it to you when you see Serena Williams last so long?
NOVAK DJOKOVIC: It is impressive. I was saying a few days ago that her attitude towards the sport, even at this age, is phenomenal. She's very committed to everyday obligations, routines, that not many players much younger than her possess.
That's something that I respect a lot, because I know the sacrifice and focus that is necessary to be able to stay there and make history, as she is doing, as she is trying to do.
I mean, over 20 Grand Slams already and she keeps on going, so it's something that I appreciate very much. I wish her the best.
Q. What do you think her rivalry with Venus has meant to tennis?
NOVAK DJOKOVIC: Well, again, I answered that question. For me it's hard to talk about it. I think this rivalry between the two sisters for me just doesn't make sense. I can't see that as a rivalry between two siblings...
Even though I respect them, the fact that they're able to kind of switch off and be on the court regardless who is across the net.
Of course they had big matches and both the them, they're great for the sport. No question about it. Don't get me wrong, but I can't talk about their rivalry.
Q. With the new renovations to Arthur Ashe Stadium, what are the differences between the one of the past and the one this year?
NOVAK DJOKOVIC: Well, I think the roof construction changed few things. First of all, the outside look. It's quite impressive. They invested a lot of money. It's great to be part of evolution of this tournament and the court that is officially the biggest court we have in sport.
It does look beautiful at the moment. The roof construction I think helped with the windy conditions. It's not as windy as it was before. It's a bit louder at night as well. You can feel that.
But it's all part of the show here. It's all part of the night session. Every Grand Slam has something unique about it. I think in New York, it's night session and the electric atmosphere that you get, the crowd interaction. It's awesome to be part of it.
Q. Were you asked tonight if you would be willing to do a mid-match interview for TV?
NOVAK DJOKOVIC: I said already. I answered that question. They didn't ask me, but I would say no anyway.
Q. They didn't ask you tonight?
NOVAK DJOKOVIC: No.
Q. The fourth set, when you broke back. Was that more the emotion of it or because they were rooting on Agut?
NOVAK DJOKOVIC: I also want to get the crowd on my side, as well. This is what you're trying to do.