Wednesday's US Open round of 64 pits Karolina Muchova against Katie Boulter on hard. Karolina Muchova has won 9 of the last 10. Katie Boulter is 4-6 across recent matches.

Karolina Muchova is clearly higher-rated on hard — our number puts Muchova around 80%. Boulter needs several things to break right at once; the percentages say they usually don't.