A spot in the next round is at stake on Monday, when Iga Swiatek goes up against Qinwen Zheng in the US Open round of 16. Iga Swiatek is rolling — 3 straight wins, 9 of 10 in recent play. Qinwen Zheng is rolling — 3 straight wins, 5 of 10 in recent play.

Neither the serve numbers nor the ratings separate these two by much, which is why our number stays close to even. The edge belongs to Swiatek — real, but not the kind you take for granted at this level.