The Tennis Channel is airing their 'All-Star Fantasy Showdown' to virtually determine the best tennis players of all-time. SI's Jon Wertheim shares what the virtual tournament is ultimately deciding and provides his picks for Tennis Channel's tournament. 

Robin Lundberg: Who is the best tennis player of all time? You know, we have these debates in every sport. But the Tennis Channel is trying to virtually give you the answer. For more, I'm joined by our senior writer, Jon Wertheim. John, you know, if you see a virtual tournament, how much do you put stock in the results?

Jon Wertheim: This is an interesting one. I mean, you mentioned I don't think any sport does this quite the way tennis does. Where everybody wants to know: would Martina Navratilova beat Serena Williams? Would John McEnroe stand a chance on grass against Roger Federer? But I think it is important to note that we have the three all-time winningest men's players now active in in Federer, Nadal, and Djokovic. That probably fuels that a little bit. But Tennis Channel has attempted to tackle this. This week, they're beholding this 'All-Star Fantasy Showdown' where it's a virtual tournament draw. But these are real matches that pit players in this conversation against each other. So that starts this week and Tennis Channel is trying to get us a real answer. I mean, look, all sports do this right? I mean, the LeBron-Jordan is a classic example, this debate that we have all the time in basketball. But I think tennis for a variety of reasons, the change in equipment and again, the fact that we have these absolute titans playing simultaneously. Tennis has this discussion all the time and Tennis Channel this week is attempting to provide some concrete answers.

Robin Lundberg: Who's your prediction for the winter?

Jon Wertheim: I'm liking Roger Federer and I'm liking Serena Williams. And we don't want to denigrate the prior generation, but I think the two titans of the sport, men's and women's, are both 38 years old and both still active right now.