March 24 (Reuters) - Defending champion John Isner unleashed 16 aces in claiming a 7-5 7-6(6) victory over determined Spaniard Albert Ramos-Vinolas in the third round of the Miami Open on Sunday.
Ramos-Vinolas broke Isner to start the match but the American saved the next four break points he faced to advance.
The seventh seed will face Britain's 19th-seeded Kyle Edmund in the fourth round.
Edmund beat Canadian 12th seed Milos Raonic 6-4 6-4.
Isner has practiced with Edmund in Miami and they have split two meetings.
Spaniard Roberto Bautista Agut also advanced after upsetting 15th-seeded Italian Fabio Fognini 6-4 6-4. (Reporting by Gene Cherry in Raleigh, North Carolina; editing by Clare Fallon)