In a game in which Kevin Garnett passed yet another milestone in his decades-long career, the Timberwolves youth movement took another bumpy ride.

Lax defense early allowed Memphis to find a comfort zone. Too many mistakes late allowed the Grizzles to pull away in a 114-106 victory at Target Center on Sunday in a game that was tied with 5½ minutes left.

Playing a fourth consecutive game without starting point guard Ricky Rubio, the Wolves made it 89-89 with 5:27 left when Shabazz Muhammad slammed home a pass from Zach LaVine, only to see the Grizzlies respond with a 15-6 run over the next four-plus minutes.

“We’ve got to work on our defense,” said Wolves interim coach Sam Mitchell after Memphis shot 56.3 percent overall and 52.9 percent (9-for-17) from three-point range. Both were season highs by Wolves opponents. They were also season highs for a Memphis team that entered the game shooting a league-low 40.1 percent from the field.

“We have to play better defense,” Mitchell added. “We rebounded enough. Overall, we didn’t turn the ball over a lot. We’ve just got to play better defense. When you don’t put pressure on those guys early and let them get in a rhythm … these are NBA players.’’

The Wolves shot 50 percent, made 19 of 21 free throws and had the edge in points in the paint, second-chance points and points on the break.

But they couldn’t stop the Grizzlies. And that started with point guard Mike Conley, who scored 20 points after being mired in a shooting slump. That included a tiebreaking three-pointer coming out of a timeout that put the Grizzlies (5-6) up for good and sent the Wolves (4-6) to their fourth home loss in four tries. He was one of six Memphis players in double figures, including four starters.

LaVine, starting again for Rubio, was limited to 17 ½ minutes by foul trouble but still scored 25 points. Andrew Wiggins had 21, and rookie center Karl-Anthony Towns, battling Grizzlies center Marc Gasol, held his own with 14 points and nine rebounds.

But at crunch time the Wolves youth showed again.

“I like to think we’re learning as we go,” said Garnett, who played a season-high 24 minutes, becoming the fifth player to surpass 50,000 minutes of playing time. “I think we’re progressing. Sam coaches really hard, demands a lot. I think it’s good for young players. They need a focus, to be pushed. … At some point it will resonate. It will hit. But these are learning days.’’

Such as learning how to close out games. The Wolves committed six of their 12 turnovers in the fourth quarter. That allowed the veteran Grizzlies to put the game away.

“There are things you do in the first, second and early third quarters that you shouldn’t do in the last six minutes of the game,” Mitchell said. “If it’s 50-50, and it’s a close game, be a little more cautious with the ball. That comes with youth.’’

And, perhaps, it will all come with time.

“We fought, that’s the main thing,” LaVine said. “We just messed up a couple times on defensive assignments. You have to be perfect on the way back.’’