BOSTON — Isaiah Thomas scored 19 points against his former team, Marcus Smart had his first career triple-double and the Boston Celtics beat the Phoenix Suns 117-103 on Friday night.

Thomas was acquired from the Suns in a trade last Feb. 19. Four days later in his only other game against Phoenix since the deal, he had 21 points and seven assists.

Smart had 10 points, 11 assists and 11 rebounds, and Kelly Olynyk added 21 points and nine rebounds.

Mirza Teletovic led Phoenix with 22 points, and Brandon Knight had 16. The Suns have lost 12 of 13 to drop to 13-28.

Boston improved to 21-19. The Celtics finished three points shy of their season-high points total, never letting the lead dip below 13 points in the second half.

Amir Johnson scored seven of Boston’s first eight points and had nine in the opening period to help the Celtics take a 36-29 lead.

Sonny Weems’ layup brought Phoenix to 46-42 with 6:26 to go in the second quarter, but a quick 6-0 Boston run pushed the lead back to double digits.

Olynyk scored 13 straight and all but three of Boston’s last 16 points in the half that ended with the Celtics up 68-47.