As hard as the Spaniard pushed, Djokovic would be there to push that much harder and end up on top.

Novak Djokovic, of Serbia, reacts breaking his opponent’s serve… But Djokovic showed the heart and stamina of a champion to rally past Agut and his wicked forehand.

“Congratulations to Bautista for hanging in there, for fighting”.

“Then we had a match“, Djokovic said.

Novak Djokovic, of Serbia, stomps on his racquet after losing the second set during his fourth round match against Roberto Bautista Agut, of Spain, at the U.S. Open tennis tournament in New York, Sunday, September 6, 2015.

“He made me work for it – there were no free points”. Djokovic responded by stepping on and snapping a racket on the sidelines, though he playfully denied it later.

“It’s always good to have a test like this in a grand slam, better earlier than later”, Djokovic said.

He could joke afterward, but Djokovic showed frustration throughout the night.

Roberto Bautisa Agut, of Spain, returns the ball during the second… Glances and shrugs at coach Boris Becker were aplenty.

Even while serving for the match, Djokovic could not relax as Bautista Agut hauled back one of the two breaks, although this would prove his last stand as he conceded defeat in his next service game.

The match lasted a healthy 3:03 and had its share of long points, including one 31-shot marathon.

Feliciano Lopez is coming off a straight sets victory over Fabio Fognini and has played 14 sets this tournament overall.

Reacting angrily, Djokovic received a code violation from the umpire for kicking out at his racquet, and his frown deepened as Bautista Agut picked up more winners with his ferocious forehand.

When the fiery Serbian – in the quarterfinals for the ninth straight year at the Open – broke back with a nifty backhanded drop volley in the very next game, Djokovic exploded with a roundhouse fist pump and put his hand to his ear, a la Hulk Hogan.

French 19th seed Tsonga reached his second quarter-final in New York with a 6-4 6-3 6-4 win over unseeded compatriot Benoit Paire, the man who opened up their section of the draw by knocking out fourth seed Kei Nishikori in the first round.

“I just want to [get] the crowd [on] my side as well”, he said.