Novak Djokovic signs autographs after his shock second-round loss to Denis Istomin at the Australian Open in Melbourne. Jason Reed / Reuters

Serb's ex-coach sure Djokovic in terminal tailspin

Novak Djokovic's former coach Boris Becker reckons the world No 2's era of dominance is over following his shock Australian Open exit on Thursday.

Six-time champion Djokovic's five-set loss to 117th-ranked Uzbek Denis Istomin - his earliest departure from a major since Wimbledon 2008 - stunned the tennis world.

The 12-time Grand Slam champion's latest calamity comes on the back of a trouble-some second half of last season during which he lost the world No 1 spot to Andy Murray and relinquished his Wimbledon and US Open titles.

After winning the French Open in June for the first time, Djokovic held all four Grand Slamtitles, but he has not won a major since.

Becker, who split with Djokovic in December after three years as his coach, said on Friday the door is now open to the next generation as the Serb nears his 30th birthday.

"I'm really shocked that Novak Djokovic lost," said Becker, who is working as a pundit for Eurosport in Melbourne.

"I thought he was playing much too defensive and never really took the initiative and never really fought for it."

German Becker, who won two of his six Grand Slams Down Under, said Djokovic's fall represents a seismic shift in the men's game.

"It's a big door open now," Becker told the New York Times. "We talked about the next gen for a long time, and now is the time for these 19-, 20-, 21-year-olds to go through the door.

"When the top dog is struggling - and no disrespect to Andy Murray, but Novak was the top dog - the way is blocked. But now it's a shift."

'Take my bags and go'

Becker said Djokovic was missing his trademark intensity and will to win in Thursday's match, and wasn't "mentally going crazy" as he used to.

Australia's former Wimbledon champion Pat Cash also believes that Djokovic has lost his aura of invincibility.

"His defeat just shows that Novak has absolutely lost his edge, there's no doubt about that," Cash told the BBC.

"I'd love to see him competing, to be a true No 2 fighting for that No 1 spot, but at this rate I don't think we will see that."

Immediately after coming off the Rod Laver Arena court where he has won six finals, Djokovic agreed that his opponents now consider him beatable.

"Sure," he said. "They wouldn't be playing against me or any other opponent or any other tournament, for that matter, if they don't believe that they can win. They go out and try their best."

Asked what he would take from the defeat, Djokovic drolly replied: "Take my bags and I go home."

Fourteen-time Grand Slam champion and 2009 Aussie Open winner Rafa Nadal is one of those who can capitalize on Djokovic's early departure from the draw.

However, Nadal said he saw nothing significant about his great rival's loss.

"What Novak did here is just amazing. Six victories, six titles. For a lot of years he has been in the semifinals, finals and winning here," Nadal said after reaching the third round.

"This is probably an accident, that's all," added the Spaniard. "He's playing well. Everybody has the chance to lose when you go on court."