The Spurs (32-6) are just the second Western Conference team to open a season 22-0 at home. Portland won their first 26 home games in 1977-78.
San Antonio led 79-74 after three quarters and opened the fourth with seven straight points to give them some breathing room in a game that featured two ties and eight lead changes.
New York made a final run in the last 5 1/2 minutes, cutting the Spurs' lead to one point on an alley-oop dunk by Kristaps Porzingis with 32.3 seconds to play.
Spurs guard Tony Parker missed a floater with 15.9 seconds left and the Knicks had a shot to win.
New York forward Carmelo Anthony drove into the lane but was well defended by Leonard and reserve guard Manu Ginobili and passed to guard Jose Calderon, whose three-point attempt with .8 of a second to play bounced off the rim as time expired.
"We got a good shot, and that was the most important thing, no matter who took the shot," Knicks coach Derek Fisher said.
"These kinds of games teach you that really have to completely empty yourself in order to be your best.
"Sometimes you still come up short and we did tonight. We had an opportunity to win the game and we didn't -- there are no moral victories."
Ginobili said he came over to help Leonard defend Anthony on the final possession in an attempt to "make things crowded."
"You know Carmelo is a guy who can shoot over almost anyone in the league," Ginobili said.
"I tried to make it crowded and then close out on Jose (Calderon) as good as I could. It was not an easy shot and Jose is a great shooter, especially from the corner."
Calderon is a 41 percent shooter from beyond the arc but said he put a little more on the shot to make sure it would not be blocked.
"In the last second, Melo (Anthony) saw me in the corner and I had a good look at the shot," Calderon said. "I thought Ginobili was close to touching it, so I shot it a little harder and I missed.
"We've grown up a lot as a team in the past few weeks and we trust each other. We did a lot of good things out there tonight that we have to continue to grow from."
The victory allowed the Spurs to pad their best home start ever and extend their win streak in AT&T Center to 31 games dating back to the final nine home games of 2014-15.
San Antonio got 16 points apiece from Ginobili, forward LaMarcus Aldridge and Parker.
The Knicks (18-20) were led by Porzingis, the rookie who poured in a game-high 28 points with a dizzying mixture of shots from long distance and in the paint and had 11 rebounds.
"(Porzingis) is a hell of a young player," Spurs coach Gregg Popovich said. "He's got drive, he's got intelligence, he's got skills and he competes."
Anthony added 20 points and 12 rebounds for New York, while Robin Lopez scored 12 points, Langston Galloway had 11 and Lance Thomas 10.
San Antonio missed three of their first four shots of the third quarter and the Knicks jumped at the chance to retake the lead at 56-54 on Anthony's deep three-pointer.
The Spurs responded behind three baskets by Parker and a ringing three-pointer from Ginobili to take a 79-74 lead to the fourth quarter.
"It's not bad to win games like that," Ginobili said.
"Nothing is easy in the NBA and we knew that the Knicks were playing great and feeling good about themselves and that we had to play much better than we have been to get this win -- and I think we did."
source: www.abs-cbnnews.com
