Kristaps Porzingis acknowledged the Boston Celtics are lacking their "killer instinct" after a troublesome season to follow last campaign's NBA glory.

The Celtics won 68 games last regular campaign and lost only three times during the post-season run to the franchise's record-breaking 18th title.

Boston, who are second in the Eastern Conference, jumped to a 21-5 start but are now only 11-9 since then, sitting 4.5 games behind the Cleveland Cavaliers.

The Celtics still managed a 122-107 win on Saturday over the Dallas Mavericks, though Porzingis admitted that his side are playing catch-up after last season's success.

"We were a lion last season, and some games this year we've looked like a house cat," center Porzingis said. "We want to have that spirit as a team this year, and it's tough.

"Obviously we can't trick ourselves and make it [like] it's playoffs every game. It's tough, just human nature.

"But we know the group that we have and we know that we're going to bring it to the big games, but we need to bring it consistently and keep building on top of good wins."

Got the W in Dallas pic.twitter.com/26cEM3UxaI
— Boston Celtics (@celtics) January 26, 2025

Boston have not had a winning streak longer than three games since November, and Porzingis knows improvements are needed if they are to defend their crown.

"We're definitely working towards getting our killer instinct back," Porzingis said after scoring 18 points against the Mavs.

"We want to have that. Some moments we've looked really good, some moments not so good. Some moments we've cruised a little bit."

Boston returned to winning ways after a humiliating loss to the Los Angeles Lakers on Thursday.

Their star forward Jaylen Brown believes the tide is turning, too, after their much-needed victory in Dallas.

"It's coming. It's coming," said Brown, who had 22 points, eight rebounds and six assists against the Mavs. "You just keep working. It's coming.

"You got to keep fighting if you want to be what you say you want to be, got to be tested and you got to pass those tests and be worthy of it. It's been hard. Shots are not going in.

"It's looked a little bit ugly at times. Our offense has been a little bit [off]. The energy hasn't been flowing the way it's used to, but that's all right.

"Just keep your mind, you keep your spirit lifted, you keep your team-mates' spirit lifted and you come out and you play basketball, the tide will turn."