This is the 21st straight French Open appearance for Djokovic, who turned 38 last week, having made his tournament debut as an 18-year-old back in 2005.
The triumph over McDonald on Tuesday extended Djokovic's record in French Open round-one matches to 21-0.
It is the most main draw appearances of any man at Roland Garros to never lose in the opening round, and the Serbian has now not lost in a Grand Slam round-one match since the 2006 Australian Open.
Incredibly, Djokovic has also never lost an opening-round match at Wimbledon or the US Open, with 19-0 and 18-0 records at each tournament, respectively.
The 38-year-old has never once been pushed to five sets in an opening-round match on the Parisian clay and has only twice been taken to four sets.
His four-set triumphs came in 2008, when he defeated former world No 59 Denis Gremelmayr â- in his first match as a Grand Slam champion â- and in 2010, versus former world No 46 Evgeny Korolev.
Djokovic's first French Open match win, and first major main draw match win, came back in 2005 as a qualifier, with an emphatic 6-0, 6-0, 6-3 victory over former US Open semi-finalist Robby Ginepri.
Notable names Djokovic has beaten in Roland Garros round-one matches include David Goffin (2013) and Hubert Hurkacz (2019), both of whom would later reach the top 10.
Another streak the Serbian will hope to continue over the coming fortnight is a run of 16 straight quarter-finals; the last time he did not make the last eight was back in 2009.
Djokovic would also hit 100 French Open match wins should he progress to the quarter-final in 2025.