Madison Keys vs Karolina Muchova — R16 — Berlin Tennis Open

Madison Keys, ranked #26, took down world #10 Karolina Muchova 6-4 7-5 on the strength of her second serve — 67% of those points won to Muchova's 40%, a 27-point swing that decided the afternoon. Muchova's four double faults, all but one in the second set, kept handing the break back, and Keys broke three times in that set alone — including the closer in game 11 after Muchova had leveled at 5-5. It's Keys' second win in two meetings, and she didn't drop serve until that lone Muchova break late.