All signs pointed to the Boston Celtics extending their five-game winning streak Sunday by beating the reeling Orlando Magic, and through two quarters, the two teams stuck to the script.

Then Boston fell apart.

The Magic overwhelmed the Celtics down the stretch in the second game of their home-and-home, ripping off a 20-5 run late in the fourth quarter. Marcus Smart nearly saved the C’s with two clutch 3-pointers with under a minute remaining, but Orlando barely held on for the 119-114 win at Amway Center.

Smart led all scorers with 26 points and went 5 of 9 from 3-point range, while Isaiah Thomas tallied 23 points and Avery Bradley added 22 points. Evan Fournier was excellent for the Magic, scoring 24 points off the bench while burying four 3-pointers to help Orlando snap an eight-game losing streak.

Isaiah Thomas, Avery Bradley, Jae Crowder, Amir Johnson, Jared Sullinger

Thomas filled it up in the first quarter to help the Celtics jump out to an early lead.

Thomas drilled three of his first four 3-point attempts and went 4 for 5 from the field to score 11 points in the game’s first 12 minutes.

Apparently Thomas’ shooting was contagious. Smart, who has been a 3-point sharpshooter of late, blitzed Orlando with three deep balls late in the first quarter, including one from way downtown right before the buzzer.

The Celtics’ second unit picked up where it left off after Friday’s stellar effort.

Jonas Jerebko, Kelly Olynyk and Smart sparked Boston’s offense early in the second quarter, and the C’s went on an 8-0 run against the Magic’s reserve unit to jump out to a 13-point lead.

Orlando’s starters didn’t sit out forever, however, and they closed the half with a 7-0 run of their own to cut Boston’s lead to single digits.

The Celtics opened the door for Orlando in the third quarter, and the Magic came barging through.

After rattling off a 9-0 run early in the frame, the C’s went ice-cold from the field, going nearly six minutes without recording a bucket. The Magic took advantage thanks to some strong play from Aaron Gordon and completely erased Boston’s 14-point lead to tie things up heading into the fourth..

Orlando victimized Boston from beyond the arc down the stretch, as Fournier and Mario Hezonja drilled back-to-back 3-pointers with under six minutes to play to start the Magic’s epic late-game surge.

Gordon brought the Amway Center crowd to its feet late in the fourth quarter with a monster putback slam.

The Celtics will head to the Big Apple on Tuesday to take on Kristaps Porzingis and the New York Knicks. The Knicks entered Sunday having lost four of their last five but beat Boston at Madison Square Garden back on Jan. 12. Tipoff is set for 7:30 p.m.

Thumbnail photo via Reinhold Matay/USA TODAY Sports Images

Thumbnail photo via Orlando Magic guard Mario Hezonja (23) shoots around Boston Celtics forward Amir Johnson (90) during the first quarter of a basketball game at Amway Center.