Q+a [q&a Andre Agassi]

The 33-year-old top seed at this week's U.S. Open is the oldest man to hold the world's No. 1 ranking. He and wife Steffi Graf are expecting their second child in mid-November.

SI: When it comes to the question of your age, are you motivated by defying conventional wisdom?

Agassi: Quite the opposite. At to be doing it. I'm thinking about being at home with the family. But I do find myself challenged. I still feel I can be better, and I still feel like I can win championships. And that needs to exist for me.

SI: What has surprised you about fatherhood?

Agassi: How much I enjoy discovering who my son [22-month-old Jaden Gil] is every day. I truly feel that every day there's something that happens that's a gift and a discovery.

SI: So how many kids are in the ideal plan?

Agassi: I'd say four, but that's from a man without that experience. We'll start with two and go from there.

SI: Do you think a part of your tennis life ended when Pete Sampras officially retired on Monday?

Agassi: Something did end, yes. No athlete is ever guaranteed to have a rivalry no matter how great his career is, and Pete and I had that. It was incredible, so something's gone that can never be recreated.

SI: Does it bother you that you'll never get another shot at him?