By Matthew Geagan, CBS Boston

BOSTON (CBS) — If the rest of the regular season is as exciting as opening night, the Boston Celtics are in for one fun ride.

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Jayson Tatum led the C’s to a 122-121 win over the Milwaukee Bucks on Wednesday night, banking in a game-winner with 0.4 seconds left to give Boston an opening night victory. Tatum finished with 30 points on the night, 21 of which came in the second half.

After the win, Tatum said that he wasn’t trying to bank it in.

“Once I let it go I knew it would hit the backboard, but I wouldn’t say I tried,” he said.

There was a little more drama in that 0.4 seconds though, as Tristan Thompson apparently fouled Giannis Antetokounmpo under the basket on Milwaukee’s inbound play, putting the reigning MVP at the line for a pair of freebies.

There didn’t appear to be any foul on the play, but the Celtics didn’t have any timeouts left so Brad Stevens couldn’t challenge the call.

But a great man once said “Ball Don’t Lie.” Anteokounmpo missed his second free throw and the Celtics escaped with the win.

It was an up-and-down game for Boston, but one that showed a lot of resolve. The C’s got off to a rocky start before using a 19-4 run late in the second quarter to take a 64-59 lead into the locker room. The run was sparked by 11 points by Jaylen Brown in the quarter, including seven straight for Boston at one point.

Brown was magnificent on Wednesday, leading Boston with 33 points off 13-for-24 shooting. He and Tatum are the first Celtics teammates to each score 30 or more points in a season opener in franchise history.

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Tatum got off to a slow start, going just 3-for-10 in the first half, but woke up and had a monster second half. He scored 12 points in the third, and put in eight straight at the end of the frame. Tatum drained a pair of threes over the final 1:04, including one with 2.2 seconds left off a Robert Williams block to give Boston a 101-84 advantage heading into the fourth quarter. The Celtics scored 37 points in the third quarter.

But the Celtics blew that lead, as Milwaukee ripped off a 23-8 run to start the fourth quarter. Giannis was a madman during that stretch with 15 points for the Bucks.

Milwaukee tied the game when Brook Lopez cleaned up a Jrue Holiday missed three, knotting the game at 113-113 with 3:36 to go. Boston gave up 19 second-chance points on the night.

Giannis gave Milwaukee a 115-113 lead when he got a friendly bounce on a jumper. He finished his evening with 35 points.

The teams went back and forth down the stretch, with a Holiday three putting the Bucks up 120-119 with 1:10 to go. Tatum missed a driving layup on Boston’s next possession, but newcomer Jeff Teague came through big with a low block on Donte DiVincenzo under the Milwaukee basket to keep it a one-point game.

Tatum hit his game-winner after the two teams traded misses. He was just 12-for-28 on the evening, but hit the biggest shot when he had to.

Teague had a great debut for Boston, scoring 19 points off 7-for-15 shooting — making all four of his threes — off the Celtics bench. Thompson got the start in his Boston debut and played 22 minuets, contributing with 12 points and eight rebounds.

The Celtics nearly blew a big second-half lead, something that plagued them throughout their NBA bubble run just a few months ago. They’re going to have an uphill battle against the better teams in the league.

But on Wednesday, the Celtics won that fight, and that’s a pretty good way to start the season.

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“We’re never going to back down no matter who is across from us,” said Tatum.