The 33-year-old player equaled the record of his childhood hero, American Pete Sampras, who ended six straight years at the pinnacle of men's professional tennis between 1993 and 1998.
In the match against Tsitsipas, Djokovic won the first two sets comprehensively, but the fifth-seed Tsitsipas staged a comeback and won the third and fourth set, sending the match into the fifth and final set.