John Isner overcame second-seeded Croatian Marin Cilic 7-6 (7-0) 6-3 at the Miami Open on Tuesday to advance to the quarter-finals.
The big-serving American will now face South Korean Chung Hyeon, who dominated Joao Sousa 6-4 6-3 earlier in the day.
In a battle of power against power, it was Isner’s booming serve that made the difference as the towering 32-year-old fired 12 aces while never giving Cilic a look at a break point on a hot, windy day.
Isner took firm control of the match in the first set tiebreak, where he stepped up his return game to shut out the world No.3 before finally breaking Cilic’s powerful serve in the second set and cruising to the win.
“I was in a very good serving rhythm today. I felt that really from my opening serve the whole match that I knew it was going to be a good serving day,” Isner said.
“I just was in a good rhythm and served much better than I did in my first two matches. I mean, percentage and aces and no double faults today. When I serve like that, I’m certainly tough to beat.”
Chung needed just over an hour to see off the Portuguese Sousa, who could not find an answer to the 19th-seeded South Korean’s relentless all-court game.
With the win, Chung advances to his second consecutive quarter-final after also making the last eight in Indian Wells, where the 21-year-old lost to Swiss Roger Federer.
Fifth-seeded veteran Juan Martin del Potro of Argentina defeated Filip Krajinovic 6-4 6-2 for his 14th consecutive victory.
The Serbian Krajinovic jumped out to an early lead in the first set when he managed a rare break of Del Potro’s serve and then held to take a 4-1 advantage in the pair’s first career meeting.
But Del Potro battled back, winning a marathon 10-minute game to take the first set before overpowering Krajinovic in the second to push his record to a career best 20-3 to start the year.
Milos Raonic’s serve was once again too much for France’s Jeremy Chardy to handle as the Canadian cruised to a 6-3 6-4 win.
Raonic, who has now won all seven of the pair’s matches, will face Del Potro in a rematch of their semi-final contest in Indian Wells, which the Argentine won en route to his first Masters 1000 title.
Spaniard Pablo Carreno Busta crushed compatriot Fernando Verdasco 6-0 6-3 to reach the second Masters 1000 quarter-final of his career.
He will face either South African Kevin Anderson or 20-year-old American Frances Tiafoe, who completed his rain-interrupted 6-7 6-2 7-6 win over Tomas Berdych earlier on Tuesday.
Fernando Verdasco, who was involved in a verbal stouch with Thanasi Kokkinakis before defeating the Australian in the round of 32, was beaten by Spanish compatriot Pablo Carreno Busta 6-4 6-4.
