Miami - Juan Martin del Potro sent his devoted fans home happy Tuesday by powering into the Miami Open quarter-finals with a 6-4, 6-2 triumph over Serbia's Filip Krajinovic.Roared on by a partisan crowd, the 29-year-old Argentinian recovered from 1-4 down in the first set to reel off nine games in a row on his way to a last-eight match with Canada's Milos Raonic on Wednesday.
Del Potro's welcome return to form and fitness saw him win the Indian Wells title and continue to impress at the last tournament in Key Biscayne before a move north to the NFL Miami Dolphins' home stadium next year.
"Playing here they make it special for the South American players and I am trying to enjoy the last time playing in Key Biscayne," Del Potro said. "I know many Argentine fans live here and are so close. I will miss them."
Windy conditions hampered players all day and the former US Open champion took time to find his groove in his first meeting with 27th-ranked Krajinovic.
"The weather was so bad to play tennis. We couldn't feel the ball 100 percent. We couldn't hit from the baseline," Del Potro admitted.
"I'm confident I will feel better tomorrow. The better weather will make me feel better on court."
Raonic, who easily saw off Frenchman Jeremy Chardy 6-3 6-4, lost to del Potro in the Indian Wells semi-finals and will be eagerly seeking revenge.
"It will be a different match to the one we played in Indian Wells, different conditions," Del Potro said. "Milos is improving and playing very solid. He has the potential to win the tournament. It will be a good match to test my fitness and see what level I'm at.
"I don't feel pressure. I am just going down my own road and seeing how far I can get. I am not thinking about ranking or anything. Just the last time here in Key Biscayne."
Del Potro is the second highest seed remaining after Marin Cilic, the second seed, was beaten 7-6 (7/0), 6-3 by American John Isner.
The Croatian's run was halted by big-serving Isner in just 87 minutes to set up a last-eight meeting with South Korean 19th seed Chung Hyeon.
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.
Isner has never won an ATP Masters event but this display has fuelled hopes this could be his time.
"I think in these events, the format is very good for me: two-out-of-three sets," Isner said.
"In a situation like that, if I'm feeling fit and healthy, which I am, and serving like I did today, I can beat a lot of people playing like that."
In the late match, impressive Alexander Zverev, the fourth seed, powered past an out-of-sorts Nick Kyrgios 6-4 6-4 to set up a meeting with Croatian Borna Coric in the last eight.
Australian firebrand Kyrgios has been struggling with an elbow injury and Zverev's power and precision was simply too hot to handle as the German reached the quarter-finals for the second year in succession.
It was a disappointing end for Kyrgios, who brought the crowd to their feet with his energetic, wild stroke play yet couldn't maintain his level consistently enough to deal with Zverev's all-round game.
"We have had great matches in the past and I am excited what the future holds for us," Zverev said. "I returned very well, that's big factor against Nick. Borna is a very good player, it certainly won't be easy."
Coric, who reached his first ATP Masters semi-final in Indian Wells earlier this month, has never got this far in Miami but showed his qualities once again with a battling 7-6 (7/2), 4-6, 6-4 triumph.
South Africa's Kevin Anderson saw off American youngster Frances Tiafoe 7-6 (7/3), 6-4 and will play Spain's Pablo Carreno Busta who dispatched fellow countryman Fernando Verdasco 6-0 6-3.
Results at the WTA and ATP Miami Open tournament on Tuesday (x denotes seeding):
Pablo Carreno Busta (ESP x16) bt Fernando Verdasco (ESP x31) 6-0, 6-3
Kevin Anderson (RSA x6) bt Frances Tiafoe (USA) 7-6 (7/3), 6-4
Alexander Zverev (GER x4) bt Nick Kyrgios (AUS x17) 6-4, 6-4
Borna Coric (CRO x29) bt Denis Shapovalov (CAN) 7-6 (7/2), 4-6, 6-4
Juan Martin del Potro (ARG x5) bt Filip Krajinovic (SRB x22) 6-4, 6-2
Milos Raonic (CAN x20) bt Jeremy Chardy (FRA) 6-3, 6-4
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
Frances Tiafoe (USA) bt Tomas Berdych (CZE x10) 6-7 (2/7), 6-2, 7-6 (7/1)
Victoria Azarenka (BLR) bt Karolina Pliskova (CZE x5) 7-5, 6-3
Sloane Stephens (USA x13) bt Angelique Kerber (GER x10) 6-1, 6-2