Devin Booker said he is "rounding third" on his road to recovery in a big boost for a Phoenix Suns side who defeated the out-of-form Boston Celtics on Friday.

The Suns triumphed 106-94 against the Eastern Conference leaders to move to 28-26 for the season and sixth in the West.

Mikal Bridges scored 25 points, while Dario Saric tallied 14 and 13 rebounds to consign the Celtics to a fourth loss in their past six games.

Booker has not played since Christmas due to a groin injury, with the Suns losing nine of the first 11 games without their All Star before rebounding to win seven of the next nine.

Donning a Detroit Red Wings knit cap, Booker was asked how his recovery was going to which he replied: "Rounding third."

Center Jock Landale welcomed the impending return of Booker and also acknowledged the importance of beating the Celtics without him.

"For us to win it without Book is big for everyone's confidence, because he will be back shortly," Landale said.

"We would have liked to win a few more games, but now that we're winning a lot of games and he's on the verge of coming back, it's big for us."

The Celtics had beaten the Brooklyn Nets by 43 points on Wednesday and defeated the Suns by 17 as recently as December, but came up short on this occasion despite Jaylen Brown and Jayson Tatum putting up 27 and 20 points respectively – albeit the duo were a combined 12-for-36 from the floor and six-for-22 from downtown.

"I thought we had some solid looks for the majority of the game," Celtics coach Joe Mazzulla said.

"But I just thought we were inconsistent in our detail."

Brown added: "We just didn't have the enthusiasm tonight. Just kind of going through the motions as a unit."

Marcus Smart missed a sixth straight game with a right-ankle sprain, with the Celtics 2-4 without the reigning Defensive Player of the Year.

"Marcus brings energy to the game," Brown said.

"He brings pace to the game. He gets us easier shots, easier looks for our guys. And defensively, he adds that tenaciousness that gets us going and picks us up in games like this."