BOSTON (CBS) — The Celtics will be fighting off elimination on Friday night. Boston lost Game 4 of the Eastern Conference Finals, 112-109, to Miami on Wednesday night, and now the Heat own a commanding 3-1 series lead.

After an impressive win in Game 3 on Saturday night, the Celtics were sluggish and sloppy throughout Game 4. Now they’ll really have their backs against the wall come Game 5 on Friday night.

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“We don’t have to win three games on Friday, we have to win one,” head coach Brad Stevens said after the loss.

Tyler Herro was on fire for Miami in Game 4, with the 20-year-old rookie leading all scorers with 37 points off 14-for-21 shooting. It seemed like any time the Celtics made it interesting, Herro was there to knock down a big shot for Miami. He drained a deep three with 4:09 left to give Miami an eight-point lead, and then made a nice cut for a driving layup with 56.2 seconds left to put Miami up 107-98.

The Celtics were able to take a brief lead in the fourth quarter and then continued to make a late push, with Jaylen Brown hitting a corner three with 16 seconds left to keep Boston’s hopes alive, making it a 107-104 game. Kemba Walker was fouled shooting a three with 9.2 seconds left to trim Miami’s lead to 109-107.

But Jimmy Butler calmly drained his pair of free throws with six seconds left, and then did it again with 1.1 seconds left to seal the victory for Miami. The Heat are now 11-2 in the postseason and just one win away from a trip to the NBA Finals.

The Celtics shot the ball better than Miami and hit more threes than the Heat, but turnovers did them in. Boston committed 19 turnovers in the game leading to 17 points for Miami. It was an overall sloppy night for Boston, with the Heat leading by as many as 12 points in the third quarter before they woke up and made it interesting again.

They also stopped attacking the basket, which had led to success in the first three games of the series. After scoring 60 points in the paint in Game 3, Boston had just 38 down low on Wednesday.

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“I don’t think we attacked enough. I don’t think we were aggressive enough,” said Walker. “We have to get back to that.”

Jayson Tatum was scoreless in the first half and started the game 0-for-6, marking the first time he had no points at halftime this season. He erupted for 28 points in the second half, including 16 in the third quarter, but also led the team with six turnovers.

“I wasn’t aggressive enough. I didn’t score in the first half and that was unacceptable,” Tatum said after the loss. “I have to play better, and that’s what I tried to do.”

Brown had 21 for Boston off 8-for-14 shooting, while Walker had 20 points and five assists.

“We have to find a way. That’s really all we can do,” Walker said after the game. “We can do it. It’s about pride, it’s about wanting to do it. Next game we have to come out and show that.”

Bam Adebayo was great again for Miami, finishing with 20 points and 12 rebounds, while Butler added 24 points and nine rebounds for the Heat.

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Game 5 is set to tip off shortly after 8:30 p.m. on Friday night.