Novak Djokovic's former coach, Boris Becker, says the Serb did not look like himself during his five-set defeat to Denis Istomin in the second round of the Australian Open.



Djokovic, who appeared more agitated during his first-round encounter with Fernando Verdasco, said he was not happy with his performance, but acknowledged that his opponent was exceptional.



"I did not recognize him, his mentality," Becker told The New York Times. "He always was very nonchalant about it, and that is not the Novak that I know. I’d rather see him break a racquet or pull the shirt or something, for him to get emotional. I thought it was very even keel the whole match through. That was unusual, and I don’t know what to make of that.



"I felt he tried, and he played five sets and four-and-a-half hours, but I didn’t see the intensity; didn’t see the absolute will to win, didn’t see him mentally going crazy."



"He was very conservative," Becker added of Djokovic's play, which allowed Istomin to take more control of the points in the fourth and fifth sets.



Djokovic's defeat follows a subpar second half of 2016, during which he won just one tournament and saw his No. 1 ranking wrested away by Andy Murray.



Murray, who fell to Djokovic in the Doha final in the first week of January, doesn't see a huge change in Djokovic's level.

"Compared with most players, it's not been that bad, really," said Murray, who added that his only truly shocking defeats were this one and the loss to Sam Querrey at Wimbledon last year. "He'd want to play his best in the majors.



"But he still won the Masters series in Canada. He was in the final at the U.S. Open. He was in the final of the Tour Finals. He beat four or five Top 10 players in the Tour Finals. He won the tournament in Doha last week. He has played some really good stuff over the last six or seven months, too. It's just not been, you know, as consistent as what it was the three years before.

"But [for him] to keep up that level for their whole career, it's just unreasonable to expect that of anyone. There's been, yeah, a couple of surprising results, for sure. But on the whole, it's not been that bad."



According to Becker, a reassessment is still required. The two stopped working together following the ATP Tour Finals in November.



"Obviously, the second half of last year there was a different priority,” Becker said. “Novak was the first one to admit that. And I think that was the main reason for me to stop this, because I thought my job isn’t that important anymore, obviously."



"I hope Novak goes back to the drawing board and remembers what made him good in the first place. If he does that, he knows what to do."



Djokovic was the defending champion at the Australian Open. He’s won the tournament six times.