Kevin Garnett scored 18 of his season-high 28 points in the first half as the new-look Boston Celtics jumped all over the Phoenix Suns early and held on for a 115-103 victory Wednesday night at TD Garden.

Garnett shot 12 of 14 from the floor and added 11 rebounds and Rajon Rondo finished with 16 points and 15 assists as Boston avenged an earlier 88-71 loss to Phoenix.

Ray Allen added 19 points and four 3-pointers for Boston, whose fans got their first glimpse of Nenad Krstic, Jeff Green and Troy Murphy. The trio combined for 20 games – 13 by Krstic – as the Celtics improved to 2-1 since the trade of beloved Kendrick Perkins to Oklahoma City.

Aaron Brooks and Jared Dudley combined for 32 points off the bench as the Suns had their four-game winning streak snapped. Channing Frye, who beat New Jersey and Indiana in overtime with game-winning 3-pointers in the Suns’ last two games, finished with four points on 1-of-4 shooting.

The Suns dropped to 3-1 during this six-game road trip which concludes at Milwaukee and Oklahoma City.

Garnett and Rondo came out on fire in the opening 12 minutes. Garnett made all five shots from the field and scored 12 points, and Rondo was 3-of-3 with five assists as Boston shot 15 of 25 for a 32-21 lead.

A 10-1 closing run in the second quarter, including a 3-pointer by Allen and a buzzer-beating drive by Rondo, provided Boston a 62-42 halftime lead. Boston pushed the edge to 29 in the third and withstood a furious rally, as Phoenix pulled within eight with seven minutes to play before Boston closed it out.