Christina Mchale defeated Elise Mertens 6-4 6-1 in the Tokyo quarter-final on hard.
Mchale C. took it in straight sets.
Mchale C. and Mertens E. faced 8 of the same opponents in the last 12 months. Mchale C. went 3–7 (30%) against them, Mertens E. 7–4 (64%). Mertens E. came out better against 3 of 7 comparable opponents, Mchale C. against 1 — though 1 of those edges carries caveats (lower-tier event).
Christina Mchale beat Elise Mertens 6-4 6-1. Umpiry, "Christina Mchale vs Elise Mertens — Tokyo Quarter-final", https://umpiry.com/match/2017-09-11/mchale-vs-mertens-tokyo-qf?utm_source=cite (as of 11 September 2017).