World number one Novak Djokovic from Serbia endured a tough return to the ATP singles circuit but battled through to beat Marton Fucsovics of Hungary 6-2, 4-6, 6-3 in the second round of the Paris Masters on Tuesday.

The 34-year-old 20-time Grand Slam champion had said on Sunday his greatest fear was lack of match practice having not played since Daniil Medvedev dashed his dreams of a Grand Slam sweep in the US Open final in September.

The Serbian's fears were borne out as Fucsovics put up a sterner test than the 'rabbit caught in the headlights' one he had produced when they met in the Wimbledon quarter-finals earlier this year. 

Djokovic barely had to engage second gear when cruising to the first set in 38 minutes with the loss of just two games.

But Fucsovics broke early to go 3-1 up in the second, energizing the evening crowd at Bercy.

Djokovic served to save the set to love at 5-3, but the Australian, French and Wimbledon champion was unable to prevent Fucsovics from serving out to take the match to a decisive set.

Djokovic, though, pulled it together in the third set and broke his 29-year-old opponent to go 4-2 up.

Djokovic had a match point on Fucsovic's next service game as he turned the screw but the Hungarian saved it and stayed in the contest by winning the game to trail 3-5.

Djokovic, though, made no mistake when he served for the match to see off his 40th-ranked opponent and progress to the third round.

He will play the winner of the all-French clash between Adrian Mannarino and the mercurial Gael Monfils.