Isner ousts fancied Cilic

Juan Martin del Potro sent his devoted fans home happy by powering into the ATP Miami Open quarterfinals with a 6-4, 6-2 triumph over Serbian 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.

"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.

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.

Raonic, who easily saw off Frenchman Jeremy Chardy 6-3 6-4, lost to del Potro in the Indian Wells semifinals 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.

Del Potro is the top seed remaining after second seed Marin Cilic 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.

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 quarterfinal for the second year in succession.

Coric 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.

Kerber exits

American Sloane Stephens had cause for a double celebration after beating Germany's Angelique Kerber 6-1, 6-2 to set up a semifinal clash with former world number one Victoria Azarenka.

She will meet two-time Australian Open champion Azarenka for a place in Saturday's final after the Belarusian beat fifth-seeded Karolina Pliskova 7-5, 6-3.

Azarenka, meanwhile, is enjoying her best tournament run since the birth of her first child last December and faces Stephens just three weeks after the pair met in Indian Wells, a match won by the American 6-1, 7-5.

Reigning Wimbledon champion Garbine Muguruza was emphatically dispatched in straight sets on Monday before Kerber received similar treatment.

Wind hampered both players, but it was Stephens who adapted far better -- the power of her groundstrokes and superior movement leaving Kerber frustrated and unable to find a way into the encounter.

Stephens took just 23 minutes to wrap up the first set as Kerber looked sluggish from the start.

Kerber was deep in conversation with coach Wim Fissette during the break, being urged to assert herself.

Kerber saved four break points in the fifth game but Stephens was did not allow her opponent into the match and a 22nd winner sealed the triumph.