Roger Federer spoke about his feelings playing an exhibition match in Buenos Aires, Argentina. The Swiss said: "My trip here in 2012 was very special. There were people at the airport and in front of the hotel, which is something you are not used to in tennis.
You can feel extra energy in the air. I am very happy to be back. I have been wanting to come back for many years but with the children, travel and tour it's not always possible and now I am excited to face Alexander Zverev although it was supposed to be Juan Martin del Potro but healthy comes first."
On his rivalry with Juan Martin del Potro, Federer added: "The hardest for me probably against Delpo was the 2009 US Open final, five sets in a final, you never want to lose. Also the two Basel finals in front of my crowd.
I had some great matches against him, including the 2009 French Open where I won in five sets, it was very close. Also at the Australian Open, close matches. I admire Juan Martin a lot, he has got one of the most incredible forehands, he is one of the good guys on the Tour, he has been great for this part of the world, South America and Argentina, it's important to have superstars."
Asked what opponents have to do to beat him, Federer concluded: "You have to practice really hard, make a lot of effort. You have to play your absolutely best to beat me and if you do not do it. Of course I try to play my matches on my racket so I decide whether if I am winning or losing.
If I play bad, I may lose. If I play well, I win. But you have to keep changing, improving, have a positive mentality because tennis can be a very frustrating sport sometimes."