At the end of the third quarter, Rajon Rondo  was getting stitches on his face, Jared Sullinger was 3-for-11 from the field and the Celtics  trailed by 15. They never quit — far from it — but still suffered a seventh loss in their last eight games, 99-90 to the Atlantic-leading Raptors. (Yes, the ones from Toronto are winning the division.)
Rondo (9 points, 15 assists) returned from an elbow to the face in the fourth quarter, and Sullinger (26 points, 8 rebounds) totaled 19 points on just six shots in the final frame, but the C’s (23-48) couldn’t erase a double-digit Raptors lead. Avery Bradley  (16 points) and Chris Johnson  (13 points) also reached double figures.
The Celtics  are currently tied for the league’s fifth-worst record.
WHAT WENT WRONG
Closing second: After regaining the lead with five minutes to play before halftime, the C’s defense fell apart. The Raptors converted their final six shots of the half, raising their field goal percentage from 40.6 to 50.0 at the break. Toronto’s nine-point halftime lead rapidly reached double digits early in the third quarter.
Interior defense: Back-to-back relatively uncontested Jonas Valanciunas third-quarter buckets punctuated a putrid night defensively for the Boston bigs and forced a Brad Stevens  timeout. Out-rebounding the Celtics  and outscoring them in the paint, Toronto’s starting frontcourt combined for 36 points and 16 rebounds in the first 30 minutes as the Raptors built a 68-54 lead midway through the third.
In stitches: A horrific third quarter only got worse when a Greivis Vasquez elbow split open Rondo’s face between his eyebrows. Replaced by Phil Pressey 5:42 into the frame, Rondo received nine stitches before returning to the bench with a bandage on his face a couple minutes into in the fourth quarter. He returned with 8:05 left.
WHAT WENT RIGHT
Mondo Rondo: The Celtics  captain singlehandedly kept them in the game through the first 15 minutes. He had his hand in their first eight field goals (2 layups, 6 assists). A couple Green drives broke up Rondo’s perfect start, but he got right back to work. When Rondo took his first breather 3:09 into the second quarter, he had impacted 13 of the C’s 15 field goals (3 layups, 10 assists), and they led 35-33.
Johnson on the rise: As he has for much of his brief Celtics  tenure, Chris Johnson  made the most of his minutes. Checking in for Green, who submitted the prototypical Jeff Green  performance, Johnson was everywhere. In 10 second-quarter minutes, he converted a 3-pointer, a pull-up 8-footer and a fast break layup while halting DeMar DeRozan‘s fast start (including a highlight reel chase-down block after Kelly Olynyk failed to convert a 3-on-1). Johnson’s effort anchored a 13-0 run that erased a double-digit Raptors lead early in the second quarter.
Sully late: After finishing 0-for-3 in the first quarter and scoring only seven points through three quarters, Sullinger erupted in the fourth. He made three consecutive 3-pointers to cut Toronto’s lead to four in the final minutes.