Celtics finish road trip in Portland Sunday night

The Celtics have dropped three of the first four games on their longest trip of the season.

Their longest trip of the season was supposed to provide the Celtics a chance to form some chemistry in the opening month.

Instead, the team that began the year favored to win the Eastern Conference is piling up some questions on their nine-day journey.

The Celtics are 1-3 heading into the trip finale on Sunday against the Portland Trail Blazers (9:05 p.m., TV: NBC Sports Boston; radio: WROR-105.7 FM).

They would have been winless through the first four games had Kyrie Irving not had an offensive explosion to lead comeback that resulted in a 116-109 overtime win over the Phoenix Suns on Thursday night.

That is the only positive that has come on the trip that has left the Celtics with a 7-5 record, four games behind the Toronto Raptors in the East.

There continue to be issues with the offense as players try to find their niches. And the defense is having trouble stopping opponents.

The Celtics hit the road with a four-game winning streak, the last victory coming over the Milwaukee Bucks, but they have stumbled since.

“As good as we were defensively in the first nine games, I don’t think we’ve been as good the last three,’’ coach Brad Stevens told reporters after Friday night’s 123-115 loss to the Utah Jazz. “I thought we actually did an OK job on the initial drives in isolation, but we didn’t get rebounds in a lot of cases. Our pick-and-roll defense, we just have to really shore it up.’’

That may be done through a change in the starting lineup as Stevens may try to get more a defensive approach right from the start.

He could go with Aron Baynes at center and move Al Horford over to power forward with either Jaylen Brown, Gordon Hayward or Jaylen Brown joining the second unit until things get straightened out.

The Celtics lost the trip opener to the Indiana Pacers when Victor Oladipo hit a last-second 3-pointer, allowed Jamal Murray to score 48 points when the Nuggets won and gave up 30 points or more in three of four quarters against the Jazz.

Brown continued his offensive woes, missing 13 of 17 shots and going 1 for 7 on 3-pointers.

The trip ends with a difficult task, the Trail Blazers off to a 9-3 start with three straight wins.

They are 6-1 at home and are averaging 117.2 points, led by Damian Lillard (26.6 points), CJ McCollum (21.0) and Jusuf Nurkic (15.1).

The Celtics will get back Irving after he missed the loss on Friday night to attend the memorial service for his grandfather.

Hayward was 3 for 9 for 13 points and had seven assists in his return to Utah on Friday. He was booed from start to finish by his former home crowd.

“I kind of expected some of that,’’ Hayward told reporters. “They were booing me from the get-go, so it’s part of the game.’’

Following the game with the Trail Blazers, the Celtics play three home games in four nights against the Chicago Bulls, the Raptors and the Jazz starting Wednesday.

Jim Fenton may be reached at jfenton@enterprisenews.com. Follow him on Twitter at @JFenton_ent.