Juan Martin del Potro's press conference after 6-2, 6-4, 7-6 win over David Ferrer.
Q. From outside it looks completely unbelievable what you've done today. Can you describe.
JUAN MARTIN DEL POTRO: From inside was the same (smiling).
I think I play a really, really nice match today. That's what I need against these kind of players, basically against David because he run a lot. He's a really good fighter. He was two set down and put me pressure all the time until the end of the match.
I think I play really focus the important moments. My best tennis came today to beat him.
Q. When you fell at the beginning, what was going through your head? Were you worried?
JUAN MARTIN DEL POTRO: Yeah, I was worried because was the same movements like four days ago. The doctor says they can't do any more with my knee. I had the tape, a very tight tape, and that help me to move a little bit, but nothing more.
I took some antiinflammatories to keep continue playing, but was really painful in the beginning of the match. I just started the match and many things come to my mind, many bad things.
But I try to be positive and play unbelievable tennis. I was lucky because I did everything good.
Q. You laid there for quite a long time and never moved. Was that because you were in agony or were you thinking about the consequences that maybe you would have to pull out of Wimbledon?
JUAN MARTIN DEL POTRO: Yeah, because is not easy when you are in quarterfinals, central court, and the match just started. I felt I did the same like four days ago. I think I was close to retire.
But to be honest, I don't want to retire in quarters for first time at the Wimbledon against David Ferrer, you know. And that's the reason for continuing play. The doctors give me good antiinflammatories. I survive my serve in the beginning of the match. I broke his serve early, and like this that give me confidence to take advantage in the beginning of the match.
Then I play confidence, be careful all the time with my movements. But in the end I did 100% and I'm so glad to go through.
Q. Was there anything you couldn't do as the match went on as far as movement or did you have everything?
JUAN MARTIN DEL POTRO: Well, I need to be 100% before the match to play against David. I didn't expect fell down in the beginning of the match, but sometimes happen.
David, what I say before, is a big fighter and he put me pressure until the last point of the match. I was thinking good things, be positive all the time. I never think about my knee after the first set.
And even if I was winning or losing, I'm be positive trying to win the match.
Q. You got through today's match. It's not long before you face the world No. 1, Djokovic. Will you be 100% for that? What can you do, because there's not much time between now and then to get your knee corrected?
JUAN MARTIN DEL POTRO: I will need to be 100% or 110% against him. He's the No. 1. He's a former champion here. It's going to be more difficult match for me like today.
But if I'm okay, if I do everything good to be ready for my next match, I will be exciting to play against him. I remember the match during the Olympic last year on the same surface.
But this time the pression is different, I know. I know it. But I will try to be ready and do my best.
Q. A nutrition question: What do you eat during a match? Do you always eat the same?
JUAN MARTIN DEL POTRO: Yeah, some gels.
Q. Are they different ones?
JUAN MARTIN DEL POTRO: No, the same ones. The same ones for like four, five years.
Q. What do they bring you? When is it exactly?
JUAN MARTIN DEL POTRO: It's like a gel. Then sometimes I eat bananas or some fruit. Nothing special.
Q. Will you do any practice at all now before the Djokovic match, or is practicing too risky for your knee?
JUAN MARTIN DEL POTRO: I will see tomorrow how I am. Now the physios are waiting for me to do the treatments.
But thinking about the Djokovic match, I need to practice tomorrow for sure. I'm confidence with my serve and expect everything good for after tomorrow.
I'm positive and I'm not thinking too much in my knee.
Q. Can you compare how you're hitting the ball now, particularly in this match, to when you won the US Open in 2009? Are you hitting it as well or better than you did when you won the US Open?
JUAN MARTIN DEL POTRO: I don't remember. It's four years ago.
But the match point I hit very well. I think 5‑All in the tiebreak, as well.
Q. I know you want to be positive, but you're obviously playing on painkillers and you're suffering. In your mind, aren't you taking a big risk with your knee, playing on it?
JUAN MARTIN DEL POTRO: I'm not going to put my body on risks, you know. The doctors tell me with this tape and taking some antiinflammatories you can play. If they say something different, I will think.
But I have the experience about injuries. I know it's the semifinals of Grand Slam. All the players feel something, some pains. It's normal.
I have my knee problem, but always the opponent, the other players, can have different injuries. You have to be strong more than the rest.
Q. People always talk about 2009, the US Open, because I think a lot of people so much want you to come back. Of course, you want to be there as well. When you won today, you just sort of dropped like a big building. I mean, just boo. What was going through your head? You've gone through a lot to get back to this point.
JUAN MARTIN DEL POTRO: Yeah, they call me the tower, not like a building.
Yeah, first because it was an unbelievable point. I think we hit really slow than the rest of the match because of the nervous. But I made my best forehand ever I think in this tournament to beat David.
And, of course many things come to my mind after the match point. It's my first semifinals here, another semifinals in Grand Slam after couple of years. I think I'm in the fight again with the top guys. That is my challenge for the future.
And be one of the only four players in this tournament, it means a lot for the future and for myself.
Q. You said you never thought about your knee after the first set. You blocked it out. What really was the level of pain looking back and feeling it now?
JUAN MARTIN DEL POTRO: Yeah, what I say before. After the first set I warmed up. I was comfortable with my body to run than the beginning. But I think the bad things are coming now after the shower, after the massage.
But the doctors are taking care of me. I'm safe. I think I will feel the same like I felt four days ago after my third‑round match. I knew everything. I need to be strong to manage the pains.
Q. About the fall again. It looked absolutely spectacular, arms and legs everywhere. Was it the worst fall you've had? Were you aware of how bad it was at the time?
JUAN MARTIN DEL POTRO: I don't try to be a spectacular fall, but was really painful for me. I was scared because I did the same thing four days ago. I know how tough is play with some pains on the knee.
But what I say, I took good antiinflammatories. I don't know what they give me, but that help me a lot.