Novak Djokovic kept alive his last-ditch bid to qualify for this year's ATP Finals by grinding out a first-round victory over Valentin Vacerot at the Paris Masters.

Likely needing to reach the semi-finals to have a chance of qualifying for the season-ending championships in Turin, the 39-year-old trailed by a set and a break and received treatment to his shoulder in the second set.

But the 24-time Grand Slam champion dug in, cut down his unforced errors and forced his opponent to return ball after ball.

While still below his best, Djokovic won 6-7 (7-5) 7-5 6-1 as his opponent, who was in form after winning the Swiss Indoors title in Basel last week, faltered.

In doing so, the Serb became the oldest man to win a match at the Paris Masters.

"Not the freshest out there after two and a half hours but I am glad to turned this match around," Djokovic told Sky Sports.

"Vacherot won in Basel and had a lot of confidence. You could feel that. His third serve is quicker than my first so it is very difficult.

"You try and find a way."

Djokovic lost in the last 16 in Basel, leaving him with a tough task to qualify for the ATP Finals for a 17th time.

He is currently 11th in the standings and, with Jannik Sinner out injured for the remainder of the season, needs to finish in the top nine to qualify.

Spain's Rafael Jodar is currently ninth, while Flavio Coboli, Arthur Fils, Frances Tiafoe and Alex de Minaur are all above Djokovic in the standings and also hoping to secure their place.

Djokovic and Australia's De Minaur could meet in the third round in Paris, with the Serb playing Australian qualifier Rinky Hijikata in round two.

He has not featured in the ATP Finals in the past two seasons because of injury but last missed out on merit in 2017.

Alexander Zverev, Carlos Alcaraz, Ben Shelton and Daniil Medvedev are already guaranteed to be playing in Turin this year.

Earlier, Britain's Wimbledon semi-finalist Arthur Fery lost 7-6 (8-6) 7-5 against home favourite Quentin Halys.

Both players held serve throughout the opening set, with Halys eventually winning the tie-break after saving two set points.

The Frenchman, who impressed on serve in particular, then fended off two break points early in the second set and earned a timely break of serve to allow him to serve for the match.

He sealed victory with a fitting ace and will now face seventh seed Tiafoe, who received a first-round bye.

Alongside a memorable Wimbledon run, Fery missed out on his first ATP 250 tournament title after losing the Winston-Salem Open final to Ignacio Buse in August.