As Celtics coach Brad Stevens answered the last question of his postgame news conference Friday following the Celtics’ 119-110 win over the Hawks, forward Marcus Morris walked down a nearby hallway wearing a Philadelphia Eagles jersey.

“E-A-G-L-E-S!’’ the Philadelphia native shouted for everyone, including to Stevens, to hear.

Stevens, who has become a Patriots supporter since befriending several members of the team’s coaching staff, smiled and joked that Morris would be suspended tomorrow.

It had turned into a feel-good day for the Celtics. Hours after fortifying their frontcourt by agreeing to a one-year deal with talented center Greg Monroe, Boston stormed to a victory over Atlanta despite being severely undermanned.

Morris, who bruised his hip when he took a hard fall in Boston’s win over the Knicks Wednesday, was sidelined and left to wear his Eagles jersey. The Celtics also were without All-Star point guard Kyrie Irving, who missed his second game in a row with a bruised thigh, as well as Shane Larkin (knee) and Marcus Smart (hand).

Boston had just 10 players in uniform, and that group was composed of six rookies, including one who was recently called up from the Maine Red Claws on a two-way contract. If ever there was a night for this team to appear discombobulated, this appeared to be it.

But they still had Terry Rozier, and over the past two games, the third-year guard has almost singlehandedly made up for absences elsewhere.

On Wednesday, he received his first start and registered his first career triple-double. He joked afterward that he never even had a triple-double in high school because he was mostly focused on pouring in points. On Friday he returned to that realm, exploding for a career-high 31 on 11-of-18 shooting, to go with seven rebounds.

“It’s just been a blessing,’’ Rozier said, smiling. “It’s been great. All the praise goes to my coaches and my teammates for allowing me to get open and just making it easy for me.’’

Rozier, who entered the night just a 35.7-percent 3-point shooter this season, made 6 of 8 attempts from beyond the arc. He had support, too.

The rookie forward Jayson Tatum, who scuffled through January a bit after shredding through his first three months as a pro, made 11 of 19 shots and scored a career-high 27 points. By the start of the fourth quarter all four Celtics starters had reached double figures.

The Knicks and the Hawks have a combined record of just 38-67, so the Celtics should flick these teams away, particularly at home. But these two wins have been valuable because of how they were built.

The Celtics overcame key absences as others stepped into prominent roles without flinching. Rozier averages 23.3 minutes per game but played 36 Friday. Abdel Nader had played more than 10 minutes in just seven games all season before averaging more than 27 over the last two.

“I just think when you’re young and you get the opportunity to play, it’s great experience when you have the responsibility of the game on your shoulders,’’ Stevens said.

Stevens relishes these situations, when he must search for lineups that on most nights would appear to outsiders to be held together by duct tape. In this case, the task was made somewhat easier by the fact that the Hawks have the worst record in the NBA.

And there were stretches during this game when Boston had four rookies on the floor at once, including the G-League call-up Kadeem Allen. But it all worked, and the Celtics improved to 38-15 and solidified their perch atop the Eastern Conference.

“I think you draw confidence from the way that the guys on the court look,’’ Stevens said. “Like, the poise they’re carrying themselves with, the aggressiveness.’’

Rozier rode the momentum from his powerful performance against the Knicks into the start of Friday’s game, making his first six shots. Without him, the Celtics could have been in trouble.

After Boston took a 14-7 lead, the Hawks responded with a 14-0 burst. The Celtics looked understandably disconnected at times. They twice fouled the Hawks on 3-pointers, and Allen entered the game and quickly had a turnover and an airball. Atlanta, meanwhile, made six of its first nine 3-pointers.

Dennis Schroder had 17 first-half points and scored 8 during one three-minute stretch in the second quarter, helping Atlanta take a 55-53 halftime lead.

But at the start of the third quarter the Celtics built a rhythm by feeding Al Horford inside, allowing him to work against the skinny and overmatched Ersan Ilyasova.

Then Rozier took over. He made all three of his 3-pointers in the quarter and scored 14 points. As a team, the Celtics were 5 for 5 beyond the arc in the third and did not commit a turnover. They outscored Atlanta, 41-20, and surged to a 94-75 lead.

“I just think he’s been more assertive,’’ Horford said of Rozier. “It’s clear for him. He sees something, he attacks it. He doesn’t like it, he passes it. He’s playing with confidence.’’

The Celtics still led, 103-84, with just under nine minutes left, and by that time the crowd was most focused on fans who appeared on the arena’s video board wearing Patriots jerseys.

But Taurean Prince scored 13 points in the first five minutes of the fourth, helping his team claw back with a 9-0 run. After a timeout, though, Rozier steadied the Celtics once again. He drilled another 3 off of an offensive rebound, and then Tatum stretched the lead back to 15 with an emphatic slam.

Adam Himmelsbach can be reached at adam.himmelsbach @globe.com. Follow him on Twitter @adamhimmelsbach.