No.2 seed Naomi Osaka defeated No.16 seed Elise Mertens 6-3, 6-3 to advance to the quarterfinals of the Miami Open for the first time in her career.

"It feels really exciting," Osaka said in her post-match press conference. "As a kid, I grew up watching players play here.

"It definitely feels very special. 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 has now won 23 consecutive matches as she eased past Mertens after just under an hour and a half of play. 

Since 2000, the only other players with winning streaks of 23 or more matches are Venus Williams, Serena Williams, Victoria Azarenka, and Justine Henin.

With both players in their first-ever fourth-round match at the Miami Open, it was Osaka who controlled the clash on return, holding 14 break points and converting for service breaks five of those times.

Osaka began to take command early in the first set when she completed a love break for 2-0 with a fiery forehand winner down the line. A litany of errors, punctuated by a double fault, caused Mertens to drop serve again and hand a 5-1 lead to Osaka.

However, Mertens made a late charge in the opener, breaking Osaka for 5-2, and then rallying from 0-40 down to hold for 5-3, saving four set points in that game alone. Incredible defense by Mertens helped her fend off two more set points in the next game, and she did have one chance to break Osaka, which the No.2 seed swatted away with an ace.

Osaka converted her seventh set point as a strong serve was returned into the net by Mertens. Osaka had 14 winners in the set, double the amount from the racquet of Mertens.

After an early exchange of breaks in the second set, Mertens needed an off-court medical timeout while leading 3-2. Upon her return, Osaka kicked into high gear, winning 12 of the next 13 points to zip ahead 5-3.

Reigning Australian Open champion Osaka continued her late surge in the set, as she would close out the match by winning a fourth consecutive game, breaking Mertens to seal victory and move into the elite eight in Miami for the first time, in her fifth appearance at the event.

Osaka's next opponent will be No.23 seed Maria Sakkari, who saved six match points en route to a 6-4, 2-6, 7-6(6) victory over No.29 seed Jessica Pegula to reach the quarterfinals in Miami for the first time.

Sakkari saved five match points during a marathon 5-4 game in the third set, then saved the sixth in the decisive tiebreak before converting her very first match point after two hours and 38 minutes of closely-contested action.

In the first set, a run of three consecutive breaks left Sakkari ahead 3-2, and she eased to the one-set lead from there. But Pegula took control in the second set as she broke Sakkari three times to tie up the match.

This is Sparta: How Maria Sakkari saved 6 MPs to edge Pegula in Miami

The decider went down to the wire as both players pummeled the ball in extended rallies, each tracking down everything and angling for the winning shot at all times. Sakkari took the early 3-1 lead, but Pegula reeled off four straight games and served for the match at 5-3. However, deep returning by Sakkari allowed the Greek to pull back on serve at 5-4.

An amazing nine-deuce game followed where Sakkari fended off four match points with bold winners and a fifth was erased after a sliding wide serve was returned wide by Pegula. Sakkari completed the difficult task with a backhand winner off of a dropshot to hold for 5-5 and keep herself alive.

The pair advanced to a decisive tiebreak, where forehand misfires by Sakkari helped Pegula pounce from a 2-5 deficit to 6-5 and a sixth match point. Sakkari slammed a return winner to save another, and then dominated a rally to move ahead 7-6 and reach her first match point. Sakkari only needed one shot, slamming a putaway and screaming with delight after her incredible feat.

Anastasija Sevastova also booked a spot in the Miami Open quarterfinals for the first time with a 6-1, 7-5 victory to end the inspiring run of Ana Konjuh.

Konjuh, a former Top 20 player who is on the comeback trail after four elbow surgeries caused her to miss much of 2018 and 2019, had pulled together a strong run, with her first two Top 20 wins since 2017 coming over Madison Keys and Iga Swiatek in the last two rounds.

But it was the exceptional court craft by Sevastova, which won out on the day, as the Latvian moved into her second quarterfinal of the season with the one-hour and 44-minute victory.

"I think overall my game was really solid," Sevastova told the press, after her win. "Didn't make any mistakes, any easy mistakes, played aggressive. My forehand was very good. I managed to hold my serve in the important moments."

Konjuh out-winnered Sevastova by 36 to 13, but she fired 11 double faults in the match. While Konjuh did convert four of her 14 break points, Sevastova was even more exceptional on return, breaking Konjuh eight times in the encounter.

Sevastova's win continues a dramatic week for the Latvian, who fought back from 2-5 down in the third set to beat Olga Danilovic in the first round, then registered her 100th WTA hardcourt main-draw win by upsetting No.31 seed Coco Gauff in the second round.

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Sevastova will now face No.5 seed Elina Svitolina in the quarterfinals.

"We had some close matches, like very close, [with] similar styles," Sevastova said. "For sure, going to be long rallies. I know how to play her. There are no secrets. We'll see. I'm confident. I'm ready to see how it is, playing against her in Miami."