Spurs coach Gregg Popovich ruled his best player out for Game 3 of the Western Conference finals on Saturday morning.
Leonard is currently ailing from a left ankle sprain. Jonathan Simmons will start in his place.
"Kawhi is out," Popovich told reporters Saturday morning at shootaround. "I spoke with Kawhi. I speak to everybody. We all speak about it. In the end, I guess it's my decision. He's not thrilled that he's not playing, but he's not ready, so we're not going to play him."
Leonard suffered the injury in Game 5 of the Western Conference semifinals against the Houston Rockets. He reinjured the ankle Sunday in the second half of San Antonio's Game 1 loss in the finals series. Tony Parker is also out.
Golden State leads the series 2-0.
Popovich declined to speculate on if Leonard would suit up for Game 4 at 8 p.m. Monday at the AT&T Center. If a Game 5 is necessary it will be at 8 p.m. Wednesday back in Oakland.
Leonard, 25, is an MVP candidate this season after posting a career-high 25.5 points per game this season. He also had 5.8 rebounds and 3.5 assists per bout, while showcasing his typical defensive prowess. The two-time Defensive Player of the Year was also a first-team All-NBA selection this season, beating out Kevin Durant for the honor for the second consecutive season.
Leonard was also averaging a career-playoff high 27.7 points per game this postseason, while chipping in 7.8 boards and 4.6 helpers per contest through 12 appearances.
No NBA team has ever won a best of seven series after trailing 3-0.