Imperious Djokovic sweeps aside Schwartzman at ATP Finals
The world number one wobbled at the start of the match against the diminutive eighth seed, making his debut at the elite eight-man event but recovered to win 6-3, 6-2.
The Serbian, 33, has enjoyed another sparkling season despite the coronavirus interruption, winning four titles including the Australian Open.
Djokovic broke again in the eighth game and won the set.
He was immediately in the driving seat in set two, breaking the Argentine, who stands just 5 feet 7 inches (170 centimetres) tall to take an iron grip on the match.
He repeated the feat in the fifth game when Schwartzman went wide with a forehand and although the Argentine added a bit of respectability to the scoreline with a hold, it just delayed the inevitable.
In the evening match in Group Tokyo 1970, Daniil Medvedev takes on 2018 champion Alexander Zverev in a rematch of last week's Paris Masters final, when Medvedev came out on top.