Playing without injured guard Tony Parker, the Spurs' depth was a huge factor. San Antonio had a 42-21 edge in points off the bench. Mason scored 12 of his 17 points in the fourth quarter and Ginobili finished with 14 points and seven assists.
The Grizzlies came in having won three straight and six of seven, including a 92-86 victory over the Spurs 13 days ago in Memphis, to move a game behind San Antonio for second place in the Southwest Division.
O.J. Mayo led Memphis with 28 points, and Zach Randolph added 19 points and 12 rebounds.
Mayo nailed a 3-pointer and Mike Conley hit two free throws after a Spurs turnover to trim San Antonio's lead to 100-95 with 33.8 seconds left, but Memphis got no closer.
George Hill, who shared time at point guard with Mason and Ginobili in Parker's absence, scored 18 points.
Seven Spurs scored in the first period as San Antonio moved to a 28-21 lead. The margin grew to 11 early in the second quarter, but Memphis chipped away. Consecutive fast-break layups by Mayo in the final minute closed the gap to a point before a short Duncan jumper with 3.9 seconds left put the Spurs up 53-50 at the break.
Duncan and Ginobili combined for 15 points in the third period, fueling a surge that rebuilt the Spurs' lead to 11 on four occasions before they settled for a 77-70 edge entering the fourth quarter.
NOTES: The next game for each team could be affected by the winter storm gripping the central United States. The Grizzlies are scheduled to host New Orleans on Saturday, but the Memphis airport was closed to most air traffic Friday. A team spokesman said the Grizzlies' plans were to fly home immediately after Friday's game, but that was subject to change, with alternative plans taking them to Nashville or keeping them in San Antonio overnight. The Spurs' next opponents, the Denver Nuggets, played Friday in Oklahoma City with a noon Sunday tipoff scheduled at the AT&T Center. ... The Spurs listed Michael Finley on their roster for the first time since Dec. 5, when he sprained his left ankle against Denver. Finley did not play.