Lleyton Hewitt refused to be drawn on his future after his 19th consecutive Australian Open appearance came to a heartbreaking end against Germany's Benjamin Becker.

Hewitt produced some inspired tennis to race through the opening two sets on Rod Laver Arena against a player who had never won a five-set match in his career.

However, the former Wimbledon champion was unable to maintain that level and Becker - who admitted to kicking a door to let off some steam after leaving the court following the second set - roared back to secure a 2-6, 1-6, 6-3, 6-4, 6-2 victory in just over three hours.

Becker's win over Andre Agassi in the third round of the US Open in 2006 prompted Agassi to retire, but the 33-year-old German said: "I hope it's not Lleyton's last match because then I get asked about it all the time. He is a great warrior, an unbelievable player, so I hope he continues."

Asked about his future plans, Hewitt - who won just one grand slam match in 2014 - said: "I'll sit down and think about it. As I've said the whole time, I haven't thought about anything.

"But obviously the Davis Cup is the next main thing. Now that we've got some guys playing really good tennis at the moment, it's an exciting time. We have a good chance to possibly pull off an upset away (against the Czech Republic in Ostrava). That's the next focus."

Earlier in the day, top seed and four-time champion Novak Djokovic lost just five games as he cruised into the third round.

World No.1 Djokovic thrashed Russian Andrey Kuznetsov 6-0, 6-1, 6-4 in an hour and 24 minutes, with all three singles matches on Rod Laver Arena in the afternoon completed so quickly that a men's doubles match was hastily added to the day schedule.

Djokovic won the first nine games against a hopelessly outclassed Kuznetsov, who received a sympathetic cheer when he finally troubled the scorers in the fourth game of the second set.

The former Wimbledon boys' champion at least had the temerity to break Djokovic at the start of the third, but normal service was instantly resumed and Djokovic closed out the match in ruthless fashion.

"After my first-round match I was hoping to have this kind of performance, especially the opening two sets," Djokovic said. "Everything went as I planned and wished, and hopefully I can stay on this path.

"(Kuznetsov) is a very talented player. He's still young and he's of the generation of my younger brother (Marko) who knows him well, so I spoke to him because I had not seen Kuznetsov play a lot."

Djokovic has dropped just two sets over the first and second rounds since 2007, winning his first title at Melbourne Park in 2008 and lifting the trophy three years in succession from 2011.

"Generally this is my most successful grand slam and the tournament where over the years I've performed my best tennis," the 27-year-old said. "The reason? I think there is not one reason. A few reasons together.

"Probably the fact that I enjoy the conditions of play. Even though the last two years the courts have played faster, significantly faster than they were before, still I do enjoy being here in Australia. Some nice, positive, easy-going, sport-oriented energy going around. People appreciate the sport and make you feel good.

"Of course it's the beginning of the year. It's the first big tournament. Everybody comes fresh and motivated. I guess in this kind of package it's a combination of things that make me feel comfortable on the court here."

Defending champion Stan Wawrinka, who ended Djokovic's 25-match unbeaten run here in the quarter-finals last year, also safely reached the last 32, but needed two hours and 16 minutes to finally subdue the resistance of Romanian qualifier Marius Copil.

The first two sets took longer to complete than Djokovic's entire match as they lasted an hour and 35 minutes, with Wawrinka winning both in tie-breaks before taking the third set 6-3.

"It was quite a tough match," fourth seed Wawrinka said. "I'm happy to get through, especially in three sets.

"The conditions weren't easy. Quite hot. Really fast on the court. And he was playing great. He was serving big, putting lots of pressure. I wasn't playing my best tennis, but I'm happy the way I fight and the way I did with the match.

"I'm happy with my game in general. To win the two first matches in three sets, it's great. I'm playing great tennis. As I say, if you want to get far in the tournament, it can be two long weeks. So you need to be ready to have some ups and downs. So far it's been good tennis. I'm happy."

Wawrinka will face Jarkko Nieminen in the third round after the Finn defeated German qualifier Matthias Bachinger in straight sets, with fifth seed Kei Nishikori taking on American Steve Johnson after coming from a set down to beat Croatia's Ivan Dodig.