How exactly does it feel to hit a serve at 150 m.p.h.? Gerardo Valero, MEXICO CITY
It's better hitting it than having someone hit it against you. But I'll take a slow one that wins me the point as opposed to a faster one that doesn't.
You definitely had your chances of winning against Roger Federer at this year's Wimbledon final. What do you think are the things that cost you the match? Andrea Kim NORTHBROOK, ILL.
I don't think there are things. In the end, he put more returns on the court than I did in the fifth set.
Do you believe that you are unfortunate to play tennis in the era of Federer and Rafael Nadal and hence not able to win as many Grand Slams as you deserve? Harish Bijwe WESTLAND, MICH.
No. You know, I feel fortunate that I get to play tennis at all. There have been great champions in every generation. Maybe not as dominant as Roger has been, but I'm certainly not going to complain about the hand that I've been dealt.
Your famous temper has mellowed. What do you attribute this change to? Kimi Chan, PROVIDENCE, R.I.
I don't think it's rare for a 26-year-old to be more mature than they were at 19. I think I've just had an audience for a lot of it. With that come some good decisions, some bad decisions. I certainly like to think I learned from a majority of them.
Why is it that American tennis just seems to be unable to produce the tennis stars that we used to? Danny Wang, ALBANY, N.Y.
Well, to me it's pretty obvious. The fact of the matter is, [tennis is] now pulling from a worldwide talent pool. We're probably the second biggest sport worldwide, and there's not really a country that's not involved in tennis right now. So with the growth of the game worldwide, the talent is going to be a lot more spread out. I think you're seeing that on a smaller scale with basketball. It used to just be, How much is the American team going to win by? Now the sport has grown so much that the Olympics are interesting again.
Who do you really idolize in the world of tennis? Roberto Juanez MIDDLEBURY, VT.
I was completely lucky and spoiled growing up. I was able to catch the tail end of John McEnroe and Jimmy Connors and lived through the golden age of American tennis with Andre Agassi and Pete Sampras and Jim Courier and Michael Chang. Even cooler than that, I've been able to establish a relationship with most of them. I'm glad that I had those guys to look up to.
Which former tennis star would you like to go up against in their prime? Michael Petrini Jr. INDEPENDENCE, MO.
It'd probably be Arthur Ashe. It'd be great to take Bobby Riggs' spot in the "battle of the sexes" too and let Billie Jean King beat up on me a little bit.
I have hardly seen you play tennis without your cap. Is it your lucky charm? Chandru Boopalam AUBURN HILLS, MICH.
No. It's just habit. It's something that I used to do in Florida when I was younger just because of the heat and sun. To be honest, now it just feels weird without it.
Why don't you like chair umpires? Octavio Barretto NEW BERLIN, WIS.