Boston Celtics' Kevin Garnett dunks in their NBA game against the Memphis Grizzlies in Boston on Sunday. The Celtics won 98-80. Michael Dwyer / Associated Press

Boston Celtics coach Doc Rivers could see Kevin Garnett was looking and feeling spry.

Running the floor and looking strong on the glass, the 35-year-old Garnett matched his season-high with 24 points and grabbed nine rebounds to lead the Celtics to their fourth straight win, a 98-80 victory over the Memphis Grizzlies on Sunday.

"He was feeling good. It's a still a kids' game. He was having fun," Rivers said of Garnett, a 14-time All-Star. "He was having a ball playing today and you don't want to tell him you have to come in because the lights are on, so we let him play in the dark a little bit."

Garnett was 9 of 12 from the field, including his third 3-pointer of the season on three tries. He hit one in Friday's win over New York.

"He's shooting it well," Rivers said, before joking about Garnett's recent 3-point success. "Gives us another option at the end of the game - don't tell him that."

Paul Pierce scored 21 points, moving nine behind Hall of Famer Larry Bird for second place on the club's all-time list, and Ray Allen added 12. Rajon Rondo had 14 assists and reserve Chris Wilcox chipped in with 12 points.

Boston took charge with a 21-7 run early in the fourth quarter that turned a six-point lead to 90-70 on Garnett's jumper.

Relying on a combination of reserves and two of their usual stars - Garnett and Pierce - the Celtics controlled the glass and outran the Grizzlies for transition baskets.

"I thought we put together some really good runs and got the ball moving," Pierce said.

Rudy Gay paced the Grizzlies with 21 points and seven rebounds, and O.J. Mayo scored 15 points for Memphis, which has lost six of eight.

The Celtics led by six points at halftime and pushed it to double digits (53-43) on Pierce's two free throws midway into the third. Boston relied on some hot long-range shooting in the third quarter, hitting 5 of its first 6 from behind the 3-point line to keep Memphis from coming back until Gay scored three consecutive baskets late in the period.

"The key to the game was that we didn't get back on defense. They had 26 fast break points on us and that was huge, and they controlled the glass," Grizzlies coach Lionel Hollins said.