A spot in the next round is at stake on Saturday, when Elise Mertens goes up against Nikola Bartunkova in the Monterrey semifinal. Elise Mertens has won 6 of the last 10. Nikola Bartunkova is 6-4 across recent matches.

On paper it's close: comparable ratings, comparable serve numbers, small margins everywhere. Mertens comes in off a compressed schedule; Bartunkova comes in off a compressed schedule. Little separates them; Mertens gets the nod on the finest of margins.