BOSTON -- Let Friday's game put to rest any suggestion that the Boston Celtics are better without All-Star point guard Isaiah Thomas.

Despite building a 14-point first-half lead against the visiting Toronto Raptors, the Celtics' offense went stagnant for much of the final 30 minutes. The Raptors outmuscled Boston at both ends of the floor while bullying their way to a 101-94 triumph at TD Garden.

For a Boston team without a signature win this season, it was another disappointing defeat with a chance to distinguish themselves despite playing without their best offensive player and someone who ranks second in the East in scoring (behind only Toronto's DeMar DeRozan).

The Raptors, on the second night of a back-to-back, went into bully mode, ratcheted up their defense, and took over Friday's game. Toronto dominated the glass in the second half (32-21 advantage), made their free throws, and never looked rattled while pulling themselves from the early hole.

The Celtics, so crisp with their ball movement while generating easy scoring chances during Wednesday's lopsided win over the Orlando Magic, defaulted to 3-point looks in the second half Friday. Eight of their 12 makes -- and 23 of their 42 shot attempts -- came from beyond the arc.

After shooting 51.5 percent overall and 57.1 percent from distance while building their double-digit lead, the Celtics then shot just 28 percent overall and 32.1 percent beyond the 3-point arc over the final 30 minutes of the game.

The absence of Thomas, one of the league's best crunch-time scorers, was abundantly clear as Boston tried to claw its way back in the final minutes. Still, coach Brad Stevens refused to use Thomas' absence as an excuse.

"Obviously, [Thomas is] a harder guy, as far as pressing up on, and with his ability to drive the ball," Stevens said. "But DeMarre Carroll didn't play for them. There's no excuses from the standpoint of not having a player available."

Asked how much Boston missed Thomas late in the game, Avery Bradley answered, "A lot. But, at the end of the day, it’s our job to execute. We can’t just win with one person; it’s a team. We need to move the ball and get the best shot for our team at the end of the game."

Add this to the list of winnable games that have gotten away from Boston. That includes Monday's visit to Houston, when neither Thomas nor Al Horford could get a last-second layup to fall in a heartbreaking loss. The Celtics have shown an ability to compete with good teams such as Toronto, Houston and San Antonio, but have simply been unable to put together the sort of full 48-minute effort that's needed to beat that caliber of opponents.

Now the Celtics will play five of their next six on the road, which includes visits to Oklahoma City, San Antonio and Memphis -- three of the top six teams in the West entering Friday's action. The Celtics are left to ponder all the little things that went wrong at key moments of Friday's game.

"That’s what good teams do; they execute at the end of the game," Bradley said.

Thomas, who missed his second straight game with a groin injury and hopes to return Wednesday against the Spurs, might not have been able to stop Boston's defensive struggles, but he might have been able to limit the painful scoring droughts. Thomas is third in the league in fourth-quarter scoring while averaging 7.7 points per game, sitting behind only Russell Westbrook and Damian Lillard. Boston's next closest player on the fourth-quarter scoring list is Bradley (49th, 4.5 points per game).

When Toronto made things tough, Boston didn't respond.

"I think they turned their energy up, got to scoring the ball," Horford said. "I felt like we had a lot of shots that didn’t go down for us that could have changed the complexion of the game. We went through like a little rut there where we couldn’t really score the ball. I had some good looks, I couldn’t knock them down. I was a little frustrated."

"It was hard for us to break their wall of defense," Stevens said. "They were pushing into us, they were very, very athletic at a number of positions, and they ratcheted it up. And it was hard for us to handle that pressure."

The Celtics remain in a crowded pack of East teams that are chasing Toronto and Cleveland.

"We still have a ways to go," Stevens said. "We've talked about it many times. If we play well against anyone in the league, then we have a chance to win. If we don't play well, we'll lose. That's just the way it is. So we have to get better, more consistent for that whole 48 minutes to ultimately be successful against this caliber of team."