Novak Djokovic vs. Roberto Bautista Agut: Score and Reaction from 2015 US Open

Novak Djokovic didn't drop a set during his first three wins at the 2015 U.S. Open, but that run ended Sunday in the fourth round against Roberto Bautista Agut. Despite that, the tournament's top seed advanced to the quarterfinals following a 6-3, 4-6, 6-4, 6-3 victory.   

Djokovic was coming off a third-round win over Andreas Seppi that he described as a "really, really tough three sets," per the Guardian's Kevin Mitchell.

"I'm satisfied, but you can always do better," the 2011 U.S. Open champ added. "We're all perfectionists in a way. We see certain things we could have done better."

In that match, Djokovic committed 31 unforced errors and allowed Seppi to have seven break-point opportunities. He also won a mediocre 45.8 percent of his medium rallies, a sure sign Djokovic was off his game.

Those problems carried over into Sunday as the 28-year-old looked sluggish from start to finish.

Djokovic's volleying—winning 11 of 13 points at the net—was one of his saving graces in the first set. He did a great job of waiting for his opportunity to get to the net and cut down the angles for Bautista Agut at the baseline.

It seemed like only a matter of time before Djokovic would pick up a critical service break in the first set, and he finally got it in the eighth game to take a 5-3 lead, as the U.S. Open shared on Twitter:

Hitting 10 unforced errors was concerning for Djokovic, though. His ball-striking left something to be desired, and he seemed to be laboring physically, which in turn affected his groundstrokes.

Still, things looked promising in the second set after he took a 4-2 lead while up a double service break. Then, Bautista Agut reeled off four games in a row, breaking Djokovic's serve twice in the process, to tie the match.

The 27-year-old Spaniard teed off on Djokovic's second serve, on which the top seed won five of 11 points, throughout the set.

In addition, Bautista Agut pummeled Djokovic from the baseline with heavy forehands. He eschewed topspin in favor of hitting flatter groundstrokes that landed deeper on the court. Instead of looking to try too hard, Bautista Agut opted for simplistic tactics, which resulted in a 59 percent success rate on medium rallies and 14 unforced errors from Djokovic.

Sports Illustrated's Jon Wertheim wasn't sure he'd ever seen Bautista Agut play this well before:

The point below offered a good example of Bautista Agut's patience paying off in a big way:

The fans inside Arthur Ashe Stadium made no bones about whom they were supporting on the night, per Ben Rothenberg of the New York Times:

Smashing his racket during the changeover did little for Djokovic to get the crowd on his side, either, per the Intercept's Andrew Jerell Jones:

Losing the second set caused Djokovic to change his strategy. He took a page out of Bautista Agut's playbook and opted for a more cautious approach, banking on his otherworldly stamina to give him the edge. Djokovic's winners went from 15 and 12 in the first and second sets, respectively, to four in the third.

But the change helped Djokovic turn the tide once again in his favor as he took the lead in the match.

He also served the best he had to that point, winning 74 percent of his first serves and 69 percent of his second serves.

Knowing he had Bautista Agut on the ropes, Djokovic moved quickly to put the match away in the fourth. His passionate celebration upon taking a 3-2 lead illustrated how much he was hoping to avoid a fifth set, per Rothenberg:

In the end, Bautista Agut ran out of gas. He mounted one last offensive in the fourth set, merely prolonging the inevitable.

Much like his win over Seppi, Djokovic can take both positives and negatives from Sunday's match. On one hand, he advanced despite not playing all that well. On the other hand, a better opponent might punish Djokovic for his mistakes and sloppy performance in later rounds.

Then again, he will play Feliciano Lopez in the quarterfinals, while a date with either Jo-Wilfried Tsonga or Marin Cilic would beckon in the semifinals. Against those three players, Djokovic holds a combined record of 31-6 in his career. All of those defeats were to Tsonga, with five coming prior to the 2012 season, according to Matchstat.

Upsets can happen at any time, but Djokovic might be able to get away with playing at 80 percent effectiveness until the final, with his biggest possible hurdles—fourth-seeded Kei Nishikori and eighth-seeded Rafael Nadal—having exited in the first and third rounds, respectively.

Note: Match stats are courtesy of USOpen.org.