Nishioka downs towering Isner despite 36-ace barrage
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Nishioka won 7-6 (7/5), 2-6, 6-3, 6-7 (3/7), 6-4 against the 2018 semi-finalist who also unleashed 87 winners.
Standing at just 5ft 7ins (1.70m) to the 28th-seeded American's 6ft 10in (2.08m), the 58th-ranked Nishioka triumphed after three previous first round exits.
The 25-year-old will face Aljaz Bedene of Slovenia for a spot in the last 32.