Basketball player Dillon Brooks delivered a game-high 24 points and Ja Morant chipped in 20 for the Grizzlies, who stayed alive in the play-in tournament with the victory in front of a pandemic-limited crowd of 7,019 at FedExForum arena in Memphis.
The Grizzlies will next play either the defending NBA champion Los Angeles Lakers or the red-hot Golden State Warriors on Friday in hopes of securing the eighth seed in the Western Conference playoffs. The eighth seed will square off with the top-seeded Utah Jazz in the opening round.
Memphis, who won five of six contests to close out the regular season, are back in the postseason for the first time since the 2016-17 season.
The Spurs were eliminated from the playoff race for the second straight season after equalling the league record of 22 straight postseason appearances.
DeMar DeRozan and Rudy Gay scored 20 points apiece for San Antonio, who limped into the play-in tournament after losing four consecutive games to finish the regular season.
Keldon Johnson added 11 points and 11 rebounds, Dejounte Murray contributed 10 points, 13 rebounds and 11 assists and Jakob Poeltl had 10 points and 10 rebounds for the Spurs.
Morant made one of two free throws with eight seconds to help clinch the win after the Spurs Gay hit a three-pointer to make it 99-96 with 9.5 seconds remaining.