Novak Djokovic kicks off 50th finals with a comprehensive win over tournament debutant Matteo Berrettini

Five-time champion Novak Djokovic kicked off the 50th ATP Finals with a comprehensive 6-2 6-1 win over tournament debutant Matteo Berrettini of Italy.

The recently-deposed world No. 1, who is locked in an intense duel with Rafael Nadal for a record-tying sixth year-end no.1 ranking, went on a run of eight games, from 2-2 in the first set, to put the match beyond the reach of Berrettini.

Although the 23-year-old Italian recouped one of the breaks back at 2-6 0-4, it proved too little too late as Djokovic soon reasserted his supremacy in the match by closing out a 6-2 6-1 win. In the process, the Serb's 36th win at the ATP Finals moves him level with Boris Becker and is only behind Roger Federer (57) and Ivan Lendl (39) for most wins at the year-end tournament.

Djokovic needs to reach the final at the 2019 Nitto ATP Finals in London to stand a chance to reclaim his no. 1 ranking and end the season as the tour's top-ranked player for a record-tying sixth time (also Pete Sampras - 1993 to 1998). The 16-time Grand Slam champion faces six-time ATP Finals winner Roger Federer and Dominic Thiem in his two remaining group-games of the tournament where another win would put him in a strong position to qualify for the semifinals.

Djokovic, who leads Federer 26-22 overall and 3-2 at the ATP Finals, last met the Swiss maestro in round robin-play at the season-finale tournament in 2015 where his 15-match win streak at the tournament was brought to an end by Federer. Djokovic won the pair's only other round-robin meeting at the ATP Finals in 2013.

The second-ranked Serb leads Thiem 6-3 in his head-to-head with the Austrian but the pair would meet for the first time at the season-ending tournament.