A spot in the next round is at stake on Wednesday, when Coco Gauff goes up against Mirra Andreeva in the US Open quarterfinal. Coco Gauff is rolling — 9 straight wins, 9 of 10 in recent play. Mirra Andreeva has won 4 in a row and 7 of the last 10 overall.

There's a wide gap in our ratings on hard, and our number follows from it. Little separates them; Gauff gets the nod on the finest of margins.