Miami - Marin Cilic, the second seed at the Miami Open, was sent tumbling out by John Isner on Tuesday as the American powered into the quarter-finals of the hardcourt tournament.
The Croatian was the highest seeded player remaining in the draw following the exit of Roger Federer but his run was halted 7-6 (7/0), 6-3 by big-serving Isner in just 87 minutes to set up a last-eight meeting with South Korean 19th seed Hyeon Chung.
It was a fine performance by Isner, the 14th seed, who rattled down 12 aces and was boosted by winning 85 percent of points on his first serve.
All three of Isner's wins over the 2014 US Open champion have now come in ATP Masters events and once a first set tie-break was negotiated in windswept conditions, the 32 year-old confidently held his nerve to send Cilic home.
"They were tricky conditions in the wind," 17th-ranked Isner said.
"So because of that I was swinging out in the first set tie-breaker. I am so happy to stay in and I am playing so well this year.
"I've started slowly over the last few years so this is great. It's going to be a tough match next but if I'm doing the right things, I can go deep here."
Results at the WTA and ATP Miami Open tournament on Tuesday (x denotes seeding):
Chung Hyeon (KOR x19) bt Joao Sousa (POR) 6-4, 6-3
John Isner (USA x14) bt Marin Cilic (CRO x2) 7-6 (7/0), 6-3
Milos Raonic (CAN x20) bt Jeremy Chardy (FRA) 6-3, 6-4
Juan Martin Del Potro (ARG x5) bt Filip Krajinovic (SRB x22) 6-4, 6-2
Frances Tiafoe (USA) bt Tomas Berdych (CZE x10) 6-7 (2/7), 6-2, 7-6 (7/1)
Sloane Stephens (USA x13) bt Angelique Kerber (GER x10) 6-1, 6-2