Celtics fall to Heat 129-121 as Boston’s loss nearly guarantees a play-in tournament berth

BOSTON — There was no embarrassing slow start from the Celtics, but the Heat just kept hitting shots as they started to build their lead in the third quarter. Boston was swept in its two-game mini-series against Miami, losing 129-121 Tuesday at TD Garden.

When the Celtics were desperately looking for a comeback bid early in the fourth quarter, the Heat found life, quickly stretching their advantage to 21 points. That was enough to bury the Celtics, who had little answers for the red-hot Heat offense. Miami finished shooting 59.3% from the field, including 53.3% on 3-pointers. Boston, once again, attempted to mount a comeback attempt in the fourth but fell short as the Heat stunted momentum through made shots.

It was a huge game for both teams in the standings as each team eyed different play-in tournament or tiebreaker scenarios. The Celtics’ loss nearly guarantees they will be in the play-in tournament as the No. 7 seed in the East.

Kemba Walker led the Celtics with a season-high 36 points as Jayson Tatum had 33 points and eight rebounds. But it was a tough day as production was limited from the bench, which finished with just 20 points to Miami’s 50. Bam Adebayo and Duncan Robinson led the Heat with 22 points each. Jimmy Butler didn’t play the second half for Miami because he was poked in the eye.

Boston was without Jaylen Brown, who’s out for the season, and Robert Williams III, who was out because of left foot turf toe.

The Celtics finish the season on a three-game road trip. They take on the Cleveland Cavaliers at 8 p.m. Wednesday at Quicken Loans Arena for the second game of a back-to-back.

Here are four takeaways from Boston’s loss to Miami:

Play-in tournament almost guaranteed: As the Celtics endured their second straight loss to the Heat, their chances of finishing in the No. 7 seed seem all but destined. The Hornets lost Tuesday; all the C’s need is at least one more win to guarantee they finish above Charlotte. With Tuesday’s loss, Boston is three games behind Miami with three games left in the season. With the Heat earning the 2-1 tiebreaker Tuesday, that means it’s impossible for the Celtics to catch them. Boston’s lone hope is New York losing out, but the Knicks have been hot and need only one more win themselves to guarantee they also finish above the Celtics.

Walker got knocked early: Only about two minutes into the game, it looked like the Celtics — already battered — were going to get another injury knock. Walker looked like he absorbed a hit to his shoulder from Adebayo. Walker quickly retreated to the locker room as the Celtics subbed in Carsen Edwards. It seemed inconsequential as Walker returned to the game quickly after, but it was a harrowing moment. Walker was huge for the Celtics all night, but his solid offensive game wasn’t enough to overcome the Heat. Walker has heated up in recent weeks, playing the best basketball of his season right before the playoffs.

Fournier with another stellar game: It seems Evan Fournier has hit his stride as he’s accumulated touches and minutes with new Celtics teammates. He scored 17 of his 20 points in the first half, which was his fifth straight game hitting double-figures. He came into Tuesday’s game averaging 21.3 points per game this month, using May as the springboard into stellar play. Fournier shot 7-for-15, including 4-for-7 on 3-pointers Tuesday.

Close out the season: The Celtics played their final home game of the season and now finish out the regular season on the road. They have a pair of winnable games against the Cavs and Timberwolves, both teams who are fighting for lottery positioning, not the playoffs. The final game of the regular season is against the Knicks on May 16 at Madison Square Garden. That game could have stakes, though New York still needs just one win to overcome Boston in the standings for good. If the Celtics are locked into the No. 7 seed soon as expected, there’s a good chance the team rests for the final few games of the season to heal any lingering injuries.