Amid Australia's Davis Cup drama at Melbourne Park, Djokovic accounted for Tsonga in a clinical performance 6-3 7-5 6-3 in just over two hours on Thursday night.

The six-time Australian Open champion next faces Canadian 25th seed Denis Shapovalov, who had a straight sets win over Japan's Daniel Taro.

Djokovic was happy with his game against a crowd favourite.

"It's always tough playing Jo," said Djokovic, who beat Tsonga to win his first title at Melbourne Park in 2008.

"He struggled with injuries in last 12 months and his ranking doesn't do justice for him at the moment - he's always been a top player in my eyes."

Djokovic said he'd never lost belief he'd return to the top of the sport after his ranking dipped to as low as 22 midway through the year.

"I have to be honest - I always believe in myself," said the 31-year-old, who battled a persistent elbow injury.

"I think that's an emotion that is always dominant."

Fourth seed Alexander Zverev also booked safe passage into round three with a grinding win over Frenchman Jeremy Chardy.

After almost four hours on court Zverev finished with a flourish to land a 7-6 (7-5) 6-4 5-7 6-7 (8-6) 6-1 victory.

Zverev next takes on Australian surprise packet Alex Bolt, who upset French 29th seed Gilles Simon in five sets.

Australian Associated Press