Japanese star Osaka into last eight at Miami Open

WASHINGTON - Second seed Naomi Osaka of Japan had a Miami Open breakthrough on Monday as she defeated 16th seed Elise Mertens of Belgium 6-3, 6-3 to advance into the quarterfinals of the tournament for the first time in her career.

Osaka has now won a staggering 23 consecutive matches as she eased past Mertens after just under an hour and a half of play.

"It feels really exciting," Osaka said. "This is one of my favorite tournaments to play, and of course I'm sad I hadn't been able to get to the second week the last times that I have played this tournament. But I'm here now, and hopefully, it will go well this time."

Osaka improves her head-to-head against Mertens to 3-1, having won their last three meetings in succession.

Osaka's quarterfinal opponent will be Maria Sakkari of Greece, who won an epic encounter in her fourth-round match.

Sakkari saved six match points en route to a 6-4, 2-6, 7-6 (6) victory over No. 29 seed Jessica Pegula of the United States to reach the quarterfinals.

Elsewhere, top seed Ashleigh Barty of Australia defeated Victoria Azarenka of Belarus 6-1, 1-6, 6-2 while fifth seed Elina Svitolina of Ukraine edged past Petra Kvitova of the Czech Republic 2-6, 7-5, 7-5.

In men's part, second seed Stefanos Tsitsipas of Greece, fourth seed Andrey Rublev of Russia and fifth seed Diego Schwartzman of Argentina advanced into the fourth round.