Alexander Zverev and Karen Khachanov meet in the semifinal at US Open on Friday. Alexander Zverev is rolling — 4 straight wins, 7 of 10 in recent play. Karen Khachanov has won 4 in a row and 6 of the last 10 overall.

Alexander Zverev simply rates much higher on hard, and our number follows from it. Khachanov needs several things to break right at once; the percentages say they usually don't.