Novak battles into last 8

 World number one Novak Djokovic reached his 26th consecutive Grand Slam quarterfinal Sunday but only after surviving a US Open scare against Spain's Roberto Bautista Agut.

Meanwhile, two-time runner-up Victoria Azarenka reached her fourth US Open quarter-final on Monday with a 6-3, 6-4 win over Varvara Lepchenko of the United States.

On the other hand, Stan Wawrinka beat Donald Young in a hard fought contest to go through to the quarter-finals. Wawrinka beat the American 6-4, 1-6, 6-3, 6-4 . It was a tough match considering that the Swede was beaten 1-6 in the second set. He however, came back well to win the game three sets to one.

The Belarusian, whose season has been stalled by a left thigh strain, appeared on Arthur Ashe Stadium with both biceps tightly strapped.

"It's a little embarrassing. I have blisters from my shirts rubbing against my arms so I needed the bandages," said Azarenka.

Lepchenko, who was bidding to become the first American woman not called Williams to make the last-eight since 2009, was broken in the third and ninth games of the opening set.

She rallied to edge ahead in the first game of the second but handed the break straight back to the 26-year-old Azarenka. The Belarus star carved another break for 5-3 before faltering when she served for the match.

But she secured victory in the next game on her first match point when left-handed Lepchenko went wide.

"I felt at 5-3 that I never went for my shots, she didn't give me much rhythm," she said. "But I told myself to be aggressive and go for it."

Djokovic, the 2011 champion won 6-3, 4-6, 6-4, 6-3 to set-up a clash against Spanish veteran Feliciano Lopez in what will also be his ninth US Open last-eight place in a row.

Djokovic gave up a 4-2 lead in the second set and saw an early break clawed back in the fourth by the 23rd seeded Agut, a former junior footballer with Villarreal in Spain.

The Serb was also broken when serving for the match at 5-2 as Agut unleashed a barrage of deep, murderous forehands before steadying himself to claim his 60th win of the year.

Defending champion Marin Cilic made the last eight for the fourth time with a 6-3, 2-6, 7-6 (7/2) 6-1 win over France's Jeremy Chardy.

French 19th seed Tsonga reached his second New York quarter-final with a 6-4, 6-3, 6-4 win over Benoit Paire.