Life without Jae Crowder hasn’t been kind to the Boston Celtics. Then again, neither have the Celtics’ opponents.

The Toronto Raptors brought their A-game for much of Friday’s contest at Air Canada Centre, and the result was a convincing 105-91 win over Boston, which now has lost four straight.

The Celtics trailed by as many as 19 points in the first half but used an excellent third quarter to pull within just five. But that’s when Raptors guard Kyle Lowry took over, pouring in 15 of his game-high 32 points in the fourth quarter to squelch any chance of a Celtics comeback.

Isaiah Thomas (20 points) was the leading scorer for a struggling Boston offense that also was without Jonas Jerebko, who sat out his second consecutive game with a sore left ankle. Evan Turner was the only other Celtic in double digits with 12 points.

The Celtics’ loss drops them all the way down to the No. 6 seed in the Eastern Conference, as the team has yet to win a game without Crowder in the lineup.

Isaiah Thomas, Avery Bradley, Evan Turner, Amir Johnson, Jared Sullinger

If you predicted Luis Scola would score 17 points in the game’s first nine minutes, well, we don’t believe you.

The 35-year-old Raptors forward got off to an incredible start, knocking down seven of his first nine shots in the first quarter. His teammates weren’t too shabby, either, shooting 55 percent from the floor and 60 percent from 3-point range to open up an early 16-point lead.

Boston didn’t do itself any favors, committing six turnovers in the frame and struggling to find any rhythm on the offensive end.

The Celtics didn’t exactly storm back in the second quarter. But on the bright side, they didn’t fall further behind.

Boston got some decent contributions from its bench in the second frame, as Brad Stevens continues to empty his bench to fill the void left by Crowder. R.J. Hunter chipped in five points that included a deep 3-pointer, while Tyler Zeller added six points and Marcus Smart chipped in a couple buckets.

The C’s cut Toronto’s lead down to 12 with a 7-0 run, but a pair of Bismack Biyombo free throws helped the Raptors take a 14-point lead into halftime.

Boston clawed back during a big third quarter by doing what it does best: forcing turnovers and running like hell.

The Celtics racked up six steals in the frame, chipping away at Toronto’s lead with a 9-1 run sparked by Bradley’s theft-and-layup:

A Terrence Ross 3-pointer and DeMar DeRozan floater had the Raptors up by 10 late in the third, but Kelly Olynyk’s floater and Hunter’s corner 3-pointer just before the buzzer cut Toronto’s lead to just five entering the fourth.

Lowry made sure that five-point deficit was the closest the Celtics would get.

The All-Star point guard scored eight points in the span of less than a minute, drilling two huge 3-pointers as part of a 14-2 Toronto run to start the fourth quarter. Boston’s offense went ice-cold, as the C’s managed just two points in the first seven minutes of the frame and committed six turnovers in the final 12 minutes.

Thomas’ 20 points included several strong finishes at the rim, but few were better than this circus layup that also drew a foul:

The Celtics will get a bit of a break — on paper, at least — after a tough stretch in their schedule. They’ll take on the lowly 76ers in Philadelphia on Sunday night, then return home Monday to take on the Orlando Magic. Tip-off for Sunday’s game is set for 6 p.m. ET.

Thumbnail photo via Peter Llewellyn/USA TODAY Sports Images

Thumbnail photo via Boston Celtics guard Isaiah Thomas (4) defends as Toronto Raptors guard DeMar DeRozan (10) dribbles toward the net in the first quarter at Air Canada Centre.