Boston Celtics star Jayson Tatum struggled mightily in the team's 109-103 loss to the Miami Heat in Game 3 of the Eastern Conference Finals on Saturday night, shooting just 3-of-14 from the field for 10 points to go along with six turnovers.

After the contest, Tatum offered a blunt assessment of his performance. 

"Unacceptable," he told reporters. "I gotta play better. I left the guys hanging tonight."

It was a surprise showing from Tatum, who averaged 28 points in the first two games of the series.

Alongside his struggles from the field, Tatum also had an injury scare, going down in the fourth quarter and writhing in pain with a stinger.

He returned to the game minutes later, however.

"My neck got caught in a weird position, and I had pain in my neck and down my arm," he told reporters. 

The Celtics will feel as though they let a winnable game slip away. Despite trailing by as many as 26 points in the second quarter, the Celtics trimmed the deficit to 15 at the half, and Heat star Jimmy Butler was ruled out for the entire second half with knee inflammation.

The Celtics cut the deficit to just one point with a little over two minutes remaining, but a 7-0 run from the Heat ended those comeback hopes. 

Turnovers were the main culprit for the loss, as Boston's 24 giveaways turned into 33 Heat points. The Heat also scored 15 points in transition.

Jaylen Brown tried to pick up the slack during Tatum's tough night, putting up 40 points, but he also turned the ball over seven times to just one assist. It was one of those nights for the team's star duo, with the Celtics now trailing 2-1 in the best-of-seven series.

"It seemed like every time we put ourselves in position, we turned it over," center Al Horford told reporters after the loss, adding that the team needs to play "with a better sense of urgency" going forward. 

That starts on Monday night, with Game 4 back in Boston at 8:30 p.m. ET on ABC. If the Celtics are going to even the series, Tatum will need to improve dramatically on his Game 3 performance.