Djokovic of Serbia in action during his match with Jan-Lennard Struff of Germany v Novak Djokovic of Serbia in the Qatar Open on Jan 2, 2017. [Photo/Agencies]

Djokovic survives

Meanwhile, Djokovic battled back from 5-1 down against world No 63 Jan-Lennard Struff to claim his first victory of the season at the Qatar Open on Monday.

The world No 2 lost his opening two service games and struggled with the German's big serves in the early exchanges.

But Djokovic rallied in determined fashion to eventually take the first-round match 7-6 (1), 6-3.

"It wasn't a great start, I was 1-5 down, it didn't look very good for awhile there," he said after winning in just under 90 minutes.

He attributed his slow start to early-season rustiness rather than any long-term concerns over his form, following a relatively poor second half of the season in 2016.

"I guess I had to get more time to get the engine started. It's the first match of the year, you never know how you're going to start," said Djokovic.

"I mean, I was a bit flat on my feet, and Struff, credit to him for playing so aggressively, hitting the serves well, and ripping the ball from the baseline.

"But I stayed composed because I knew, I believed that I could find the rhythm, start reading his serve better, and that's what happened."

Djokovic, who is the defending champion in Doha, hit 17 winners but also 20 unforced errors. His opponent thundered down nine aces.

The 12-time Grand Slam winner is looking to reclaim his No 1 ranking from Britain's Andy Murray, who is also in Doha, and is the tournament's No 1 seed.

If the matches go as expected, the archrivals will meet in a tantalizing final on Jan 7.