A look inside the Hawks’ 104-95 overtime loss to the Celtics Sunday:

Three key players

Paul Millsap: The Hawks all-star forward had 45 points, 13 rebounds and four blocks. His 26 points in the first half were as many as he had in the first three games of the series combined.

Isaiah Thomas: The Celtics point guard finished with 28 points, six assists and four rebounds.

Marcus Smart: The Celtics reserve guard finished with 20 points, eight rebounds and five assists.

Five observations

1. Get Smart

Paul Millsap had 45 points but none after the Celtics put Marcus Smart on him defensively midway through the fourth quarter. The smaller Smart stood up to the challenge. The one player the Hawks counted on to score was silenced. “Well, he guarded Millsap the last thirteen minutes of the game, including overtime, probably; maybe the last eight minutes of the fourth quarter,” Celtics coach Brad Stevens said of the strategy. “Obviously you’re throwing darts a little bit with a guy that’s rolling like that. But one thing about that is, when you’ve scored 45 through three quarters you probably are a little winded.”

2. Public enemy No. 1

Dennis Schroder is still a hated man in Boston. Maybe more than Mike Bibby now. Schroder was involved in an incident with Celtics’ Isaiah Thomas in Game 3 which led Thomas being given a Flagrant Foul 1 after NBA review. The TD Garden fans boisterously booed Schroder he touched the ball on Sunday. He was called on early after Jeff Teague picked up two early fouls. It got worse when Schroder got tangled with the Celtics’ Jae Crowder late in the second quarter and got a technical foul. It appeared Crowder kneed Schroder in the stomach before he shoved back and got his second technical of the series.

3. Overtime drought

The Hawks woeful record in overtime games continue. After going 0-5 in overtime during the regular season, the Hawks dropped another in extra time. The Hawks shot 1 of 11 in the extra period. Their failure to execute in such situations is an issue. “I can’t put my finger on it,” Millsap said. “I think it’s something as a group we have to figure out. Because we have lost a lot of games in overtime. We have the guys to do it. I think we are smart enough to figure it out.”

4. Scott off the bench

The Hawks first substitution had to be Schroder for Teague in the first quarter. The Hawks’ substitution at center, usually their first reserve, was Mike Scott for Al Horford. In the series, Mike Muscala has been the first big off the bench. However, with the Celtics using a small lineup, Scott got the call. Kris Humphries has been a DNP-CD all four games. Hawks coach Mike Budenholzer said Saturday that playing Humphries has been considered but it’s clear the team does not see him as a viable matchup against the Celtics.

5. Game times

With the Cavaliers sweeping the Pistons in their first-round series Sunday night, Game 5 of the Hawks-Celtics series will be at 8:30 p.m. on TNT nationally and Fox Sports Southeast. There are two scenarios for Game 6 on Thursday in Boston. The game will be at 7 p.m. if Game 6 is necessary in the Oklahoma City-Dallas Western Conference series. The game will be at 8 p.m. if there is no other game. The game will also be on TNT and Fox Sports Southeast.