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The Serbian won the match 7-6(4) 6-3 at the O2 Arena in London on Monday.
Djokovic struggled in the first set as Tsonga emerged as the better player, but the Frenchman failed to convert his chances.
Djokovic eventually triumphed in a tiebreak in the opening set before an early break in the second saw him ease to a victory.
He will now face Andy Murray on Wednesday.