BOSTON (CBS) — There is no quit in these Boston Celtics, but we already knew that.

Their heart and grit were on full display Thursday night in Game 3, as the C’s battled hard for every loose ball, got tough when they had to, and never gave up even when they were facing a double-digit deficit in the fourth quarter.

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But all that got them was a 103-95 loss, and a 3-0 hole to the Cleveland Cavaliers. Now they face a must-win in Game 4 on Sunday, or their season will be over.

“Our effort was great. We played really hard, but we have to play better,” Celtics head coach Brad Stevens said following the loss. “We’ve said it over and over, it’s an eight-point game at the end of the day and there are so many possessions we threw away.”

Stevens said Cleveland showed great poise during the game, something his Celtics did not.

The Celtics had their chances, but the Cavaliers are just better. Boston had a four-point lead just ahead of halftime, but the Cavs closed the first half on a 12-0 run to take an eight-point lead into the locker room. The Celtics came close at times in the second half, pulling within five in the game’s final minutes, but Cleveland never relinquished their lead and now are one win away from advancing to the Eastern Conference semifinals.

“We played with tremendous energy and great spirit, we just didn’t make good, solid basketball plays tonight,” said Stevens.

Here is what we learned from Boston’s Game 3 loss:

No Quit In Crowder

 (Photo by Brian Babineau/NBAE via Getty Images)

(Photo by Brian Babineau/NBAE via Getty Images)

Jae Crowder said he wouldn’t be intimidated by LeBron James, and he wasn’t. Crowder played hard until the very end, as all of the Celtics do, but his energy was at a whole new level at the end of the game. He was the force behind Boston’s mini-comeback-that-wasn’t in the fourth quarter.

“He’s not going to back down from anyone,” Stevens said of Crowder. “He made huge shots. He made huge plays at the rim for us.”

Crowder finished the night with 16 points, seven rebounds, and four assists in 31 minutes. He finished the night 5-for-6 from the floor, including 2-for-3 from three-point land, and may find his way into the starting lineup in Sunday’s Game 4.

If anything, he probably made himself some more money in the offseason. Here’s hoping he gets that from the Celtics.

Isaiah Thomas Is Human

Thomas has been so great since coming over from Phoenix, but he really hurt the Celtics in Game 3. Thomas had just five points on 2-for-9 shooting in his 21 minutes on the floor.

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Love Can Be A Big-Game Player

Kyrie Irving was the star in Game 1, with LeBron taking those honors in Game 2. James had 31 points in Game 3, but it was Kevin Love’s turn for the spotlight.

Love got going early and never let up, finishing the night with 23 points and nine rebounds. He hit five three pointers, including one with 2:13 left to push Cleveland’s lead to six, and another with 26 seconds left and the Cavs up five (off a Tristan Thompson offensive rebound) to seal the win.

Love’s future in Cleveland is unclear, but it looks like he can play well in Boston.

Sully Can Have An Impact

(Photo by Brian Babineau/NBAE via Getty Images)

(Photo by Brian Babineau/NBAE via Getty Images)

Jared Sullinger made a big impact in the second quarter before getting into a bit of foul trouble. He finished the night with 10 points off 4-for-6 shooting and eight rebounds in 17 minutes.

Stevens Willing To Switch It Up

Stevens kept his starting lineup the same to start the game, but had no problem changing things up to start the second half.

Stevens went with Jae Crowder and Jonas Jerebko over Marcus Smart and Brandon Bass, respectively, to start the second half, and he was rewarded for it. The Celtics went on an 8-0 run to tie the game at 56-56.

The C’s coach didn’t change things up to start the game because his team had solid starts in Games 1 and 2. But after coming out a little flat in Game 3 in front of their home crowd, Stevens may have to consider putting Crowder in the starting five for Sunday.

Celtics Can’t Defend The 3

The Cavaliers were 12-for-29 from downtown on Thursday night, and have hit 27 triples in the series (compared to Boston’s 19). Their ability to spread the floor has been a real difference in the series.

It Could All Be Over On Sunday

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Yes, Sunday may be the final game of the season for the Celtics. But don’t expect them to go down without a fight.