"You've got to keep going, especially if you get up," he said.
It's a concept Spurs point guard Dejounte Murray knows well.
LaMarcus Aldridge had 22 points, Bryn Forbes added 20 and San Antonio rallied for a 120-111 victory over the Knicks on Wednesday night, spoiling Barrett's debut.
The Spurs outscored the Knicks 37-27 in the final quarter after Barrett rallied New York from a 16-point deficit in the first half. Barrett scored 21 points on 9-for-13 shooting with five rebounds and two assists in 37 minutes.
"You've got to keep putting it on them," Barrett said. "Just like we're not going to quit, they're not going to quit either."
The Knicks have pinned a great deal of hope on Barrett, the No. 3 overall draft pick out of Duke, after failing to sign any marquee free agents in the offseason.
"I told you," New York coach David Fizdale said. "When the popcorn's popping, that kid is ready."
Marcus Morris led New York with 26 points, and Julius Randle added 25 points and 11 rebounds.
The Spurs are similarly counting on Murray, who played in his first game since tearing his right ACL in a preseason game last October.
"I'm blessed, I'm thankful," Murray said. "I put in the work, but I've got a lot of work to do. A year ago today I was at home, I couldn't walk, and a year later I'm playing. So, I'm thankful."
Murray had 18 points, including a 3-pointer with five minutes remaining that put San Antonio up 105-97. The 6-foot-5 point guard had six assists and eight rebounds.
"I thought he was aggressive, tried to do what we wanted to do and played pretty good defense," Spurs coach Gregg Popovich said. "Probably needs to take care of the ball a little bit better, but overall after being out so long, he's come a long way pretty quickly."
Murray had four turnovers and San Antonio committed 21 as a team, which led to 32 points for New York. The Spurs did not have any turnovers in the fourth quarter, however.
New York started Barrett, Randle, Morris, Bobby Portis and Alonzo Trier, but Fizdale said the lineup could change as soon as Saturday against Washington, especially at point guard.
Barrett started at point guard, but veteran Elfrid Payton had nine points and four assists in the second half while running the point with Barrett at off guard.
Knicks: Morris, who signed with the Knicks after backing out of a verbal agreement with the Spurs on a two-year deal, was heavily booed throughout the game. Morris responded to the initial boos by backing down and then hitting a turnaround jumper on DeMar DeRozan for the game's opening points. ... The Knicks signed F Ivan Rabb to a two-way contract. The 6-foot-10, 220-pounder averaged 5.7 points, 4.3 rebounds and 1.0 assists in 14.6 minutes over two seasons with the Memphis Grizzlies. He will primarily play for New York's G League affiliate, the Westchester Knicks.
Spurs: Trey Lyles, who the Spurs signed after Morris reneged, started at center and had eight points and 11 rebounds. ... Popovich opened his 24th season as San Antonio's coach, setting the record for most seasons coaching one franchise. Popovich was previously tied with Utah's Jerry Sloan. ... Popovich acknowledged the Spurs fully guaranteed the final year of Aldridge's contract. Aldridge was guaranteed $7 million for 2021 before the Spurs picked up their option Wednesday to fully guarantee his $24 million contract. ... Popovich, Larry Brown, Hubie Brown and Bill Bertka are the only coaches to serve as an NBA head coach in their 70s in league history. Popovich turned 70 on Jan. 28.
Knicks: Host Washington on Saturday night.
Spurs: At Brooklyn on Friday night.
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Barrett drops 21 in Knicks debut
RJ Barrett has it all working against the Spurs, scoring 21 points on 9-of-13 shooting with five rebounds, but the Knicks fall to the Spurs 120-111.