Solid and confident: Novak Djokovic destroys debutant Matteo Berrettini in Nitto ATP Finals curtain-raiser

Serbian tennis icon Novak Djokovic confidently began his campaign to reclaim the year-end number one ranking by beating Italian debutant Matteo Berrettini 6-2, 6-1 in the ATP Finals opener.

The second-seed Serb, who has been drawn in the Bjorn Borg Group, needed just 64 minutes to beat his less experienced opponent.

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Berrettini, who is the first Italian to qualify for the season-ending event since 1978, could do nothing to best the 16-time Grand Slam winner who fully controlled the rhythm of the game.

"It feels great to be back in London," Djokovic said after his win. “It was not easy for him to be playing his first Tour Finals match and I knew he might be a bit nervous. Fortunate to get the break and then I started reading his serve better and played solid throughout the match."

Djokovic entered the tournament 640 points behind Rafael Nadal and has now cut the deficit to just 440 points in the battle to end the year on top of the ATP rankings.

The 32-year-old needs to reach the final of the season-ending showpiece to reclaim the number one spot from Nadal and match Pete Sampras's incredible record of finishing six separate seasons as the world's number one player.

Nadal, who has been placed in the Andre Agassi group, will start his ATP Finals quest on Monday with a match against defending champion Alexander Zverev of Germany.