A spot in the next round is at stake on Friday, when Elena Rybakina goes up against Jessica Bouzas Maneiro in the US Open round of 64. Elena Rybakina is rolling — 5 straight wins, 9 of 10 in recent play. Jessica Bouzas Maneiro has won 5 of the last 10.

The serve is where this match separates: Rybakina has been winning 70% of first-serve points to Maneiro's 59.5%, and on hard that gap compounds fast. Maneiro needs several things to break right at once; the percentages say they usually don't.