The pair have enjoyed a strong bond since 2021 but there was no quarter given in a see-sawing first set as they swapped early breaks before Badosa attacked Sabalenka's powerful serve in the sixth game, edging ahead with a return that hit the net cord.
That spurred Australian Open champion Sabalenka into action and the big-hitting 26-year-old broke back and let out a scream that was met with huge cheers from fans on Philippe Chatrier court, before recovering another loss of serve later.
Last year's semi-finalist hit a monster forehand to go up 6-5 and came up with a delightful backhand slice from the deep en route to closing out the opening set, as world number 139 Badosa reflected on her missed opportunities.
The former world number two, who has struggled with a back issue in recent years while Sabalenka claimed two Grand Slam titles, got off to a bad start in the next set as her Belarusian opponent reeled off four games in a row.
Sabalenka produced a superb drop to set up match point and the knockout blow came in the form of an unforced error from the racket of Badosa but was immediately followed by a warm hug at the net.
