WASHINGTON — Two nights after receiving their NBA championship rings and watching Banner 18 climb to the TD Garden rafters for a win over the Knicks that was basically one big celebration, the Celtics returned to a more monotonous reality Thursday.

When their game against the Wizards started, about half of Capital One Center was full, and about half of the people were there to support Boston. Fans here are aware that the Wizards will once again be one of the worst teams in the NBA this year, and opening night, a night usually full of possibilities, might not breathe life into this building.

And the lower tension seemed to affect the Celtics’ focus at the start, but they made sure it didn’t linger. After falling behind by eight points early, Boston had little trouble taking control and coasting to a businesslike 122-102 victory.

Jaylen Brown, who turned 28 on Thursday, had 27 points to lead the Celtics (2-0). Jayson Tatum added 25 points and 11 rebounds.

Sam Hauser was left out due to lower back soreness, and there is a chance he will remain sidelined after this match. Before facing the Wizards, coach Joe Mazzulla indicated he wouldn’t necessarily fill Hauser’s minutes by tagging players with similar size and skills. Sure enough, he relied heavily on his big men, often deploying two at a time. The four-man bench rotation that Mazzulla used for most of the evening included three bigs: Luke Kornet, Xavier Tillman and Neemias Queta.

Less than two minutes into the first quarter, a referee bumped into a fan carrying a tray full of beer, sending foam flying across the hardwood and causing a delay as workers with towels rushed to the spill site. Everyone just stood around waiting.

The Celtics seemed to suffer from the lack of energy at the start. They had a few early turnovers, surrendered a few offensive rebounds and just didn’t seem quite in sync.

It didn’t help that Jordan Poole couldn’t miss. The former Warriors standout is an erratic shooter, but he can catch fire. And he started by making six of eight shots and five of seven 3-pointers during a strong 17-point opening quarter.

The Wizards led by as many as 8 points in the period before the Celtics pulled away behind Tatum.

The Celtics’ start was quite aggressive in the opening quarter, doing most of its work inside the arc. Eight of his nine shots in the first quarter were two-pointers, and he also attempted seven free throws in the final 66 seconds. Even though he missed three, his goals were enough to give Boston a 33-32 lead at the start of the second.

It helped that the wizards are, well, still the wizards. They fouled Boston’s three-point shooting twice in the first half and coughed up 10 turnovers.

Late in the second quarter, Tatum’s eyes went wide when seven-foot rookie Alex Sarr switched to him. He swirled and swung twice and had no trouble creating space for three-pointers, the second giving Boston a 60-53 lead. Tatum went into halftime with 20 points and 10 rebounds.

Brown had a quiet 1-of-6 start, but he had no trouble shaking it off. Late in the second quarter and early in the third, he overpowered the smaller Wizards around the basket. After converting a three-point play by backing Poole up, he leaned forward and held his hand above the floor because the universal sign for Poole was too small.

Brown then finished off the Wizards by hitting a pair of 3-pointers in the first 40 seconds of the fourth quarter. After the second, he walked toward the baseline and waved to the crowd.

Adam Himmelsbach can be reached at [email protected]. Follow him @adamhimmelsbach.