I'm joined by Amy Lundy, freelance tennis journalist for ESPN and FiveThirtyEight, to discuss the 2009 US Open semifinal between Serena Williams and Kim Clijsters. Before we get to the match, we hit on what needs to happen before tennis comes back, and how Amy compiles data and metrics for her articles. Later, we discuss the similarities between Williams and Clijsters on and off the court, why Serena hasn't won a major since coming back from maternity and what can be expected out of Clijsters most recent comeback.