World number one Novak Djokovic was struggling to play his best, but held firm when pressed to the brink Tuesday and battled into the ATP and WTA Miami Open quarter-finals.
The two-time defending champion outdueled Austrian 14th seed Dominic Thiem 6-3, 6-4, stretching his Miami win streak to 13 matches to book a last-eight date Wednesday against Czech seventh seed Tomas Berdych.
“Straight set win but far from easy. It was a tough match,” Djokovic said. “I kept my serves. But I made a lot of double faults and he had me under a lot of pressure.”
Djokovic, a five-time Miami winner overall, rescued 13 of 14 break points, four of them in the last game of the first set and four more in a dramatic 14-minute final game before hitting a forehand winner on his fourth match-point opportunity.
“I had some luck in that last game where he missed a couple of easy forehands to get the break back and get into the match,” Djokovic said. “I stayed tough when it was most needed. The important moments I tried to make him play, make him run.”
Djokovic won his 11th Grand Slam title two months ago at the Australian Open and has also lifted Doha and Indian Wells trophies this year while Thiem captured titles last month at Acapulco and Buenos Aires.
The 28-year-old Serbian made eight double faults and 29 unforced errors against only two aces and eight winners.
“The second serve was not working that well. That was due to the pressure he was imposing. I just didn’t have the rhythm,” Djokovic said.
“Generally I don’t get to face that many break points. I’ll try not to get myself in those positions as much.”
Berdych outlasted French 10th seed Richard Gasquet 6-4, 3-6, 7-5, but has won only two of 24 meetings with Djokovic, having lost their past nine matches since a 2013 Rome quarter-final victory.
They are the only top-10 men still playing except for Japanese sixth seed Kei Nishikori, who downed Spanish 17th seed Roberto Bautista Agut 6-2, 6-4.
“I played really well,” Nishikori said. “I felt great out there.”
Up next for Nishikori, who won his fourth consecutive Memphis crown last month, is French 16th seed Gael Monfils, who rallied past Bulgarian 26th seed Grigor Dimitrov 6-7 (5/7), 6-3, 6-3.
“He is playing really well,” Nishikori said. “He is a fun player to play against and we will have a good match.”
Nishikori won their only prior meeting in 2014 on Halle grass.
“Kei is a good player, very consistent, and he has a win over me,” Monfils said. “It will be a great match.”
Only one of the world’s top 12 women, second-ranked Angelique Kerber, is still playing after Romanian fifth seed Simona Halep was ousted 4-6, 6-3, 6-2 by 19th-ranked Swiss Timea Bacsinszky.
“To beat someone who fights as hard as she does, it’s something amazing,” Bacsinszky said. “I’m happy with it.”
The 2015 French Open semi-finalist will play for a berth in the final against Russian 15th seed Svetlana Kuznetsova, the 30-year-old two-time Grand Slam winner who ousted top-ranked defending champion Serena Williams in the third round.
Kuznetsova, the 2006 Miami champion, beat Russian 30th seed Ekaterina Makarova 6-7 (3/7), 6-4, 6-3.
“Just kept fighting,” Kuznetsova said. “I was feeling low in energy but I tried to hang in there.”

Kyrgios rants on ‘biased’ nature of ‘ruined’ sport
Australian Nick Kyrgios unleashed a tirade on tennis as a “biased” and “ruined” sport Tuesday during his fourth-round triumph at the ATP and WTA Miami Open.
The 20-year-old from Canberra defeated 51st-ranked Russian Andrey Kuznetsov 7-6 (7/3), 6-3 to become the first Aussie in the Miami quarter-finals since Lleyton Hewitt’s 2002 semi-final run.
But a dispute flared in the first set after chair umpire Cedric Mourier called a code violation against Kyrgios for swatting a ball tossed his way by a ballperson into the stands.
On the next changeover, Kyrgios told the umpire his action wasn’t intentional and said a star player such as 14-time Grand Slam champion Rafael Nadal would not have been called out for the same action.
“Anyone else, like Rafa did that, you would keep it cool,” Kyrgios said.
“This game is biased as anything. You all know it as well. It’s biased as shit, this game. What else has it got to hide? It’s ruined. Absolutely ruined.”
After the match, Kyrgios said only that he stood by the comments. Kyrgios, the youngest player ranked in the ATP top 30 at 26th, will face Canadian 12th seed Milos Raonic today’s for a semi-final berth.
Off to a career-best 13-3 start that includes his first ATP title last month at Marseille, Kyrgios has a track record of making off-color remarks.
Last year he drew almost blanket condemnation throughout the tennis world for lurid remarks about Stan Wawrinka’s teenage girlfriend during a match against the Swiss star in Montreal.