BOSTON -- As the Dallas Mavericks essentially waved the white flag, substituting for all of their starters while trailing by 21 points with 2:37 remaining in Monday's Game 5, Kyrie Irving walked toward the other end of the floor to congratulate his former teammates Jaylen Brown and Jayson Tatum, as well as other members of the Boston Celtics.

Irving returned to the bench and exchanged an embrace and a few words with his teammate Luka Doncic, a superstar wrapping up his first NBA Finals appearance.

"We said, 'We'll fight together next season, and we just going to believe,'" Doncic said after the Mavericks' 106-88 loss to the Celtics, who clinched their record-breaking 18th NBA championship.

Irving described it as a "bitter" ending to a "really positive journey" for the Mavericks, who reconstructed the supporting cast around their star tandem over the past year, bouncing back from a lottery finish to win the Western Conference.

The anticipation within the organization is that the Mavs, led by their 25-year-old five-time first-team All-NBA selection, can be a contender for years to come.

"We answered a lot of questions this year on what we were capable of doing and now it's just about being consistent," said Irving, who struggled again at TD Garden, finishing Game 5 with 15 points on 5-of-16 shooting. "I think probably in the last week, I said that I wanted to be remembered as one of the best teams of this era and our last few champions have been a new one each and every year.

"So, I see an opportunity for us to really build our future in a positive manner where this is almost like a regular thing for us, and we're competing for championships. You know, I think from a spiritual standpoint, I think I enjoyed this journey more than any other season, just because of the redemption arc and being able to learn as much as I did about myself and my teammates and the organization and the people that I'm around."

Doncic, who had 28 points, 12 rebounds, 5 assists and 7 turnovers in the elimination loss, wasn't in much of reflective mood Monday night. However, he did say he felt "great" about the franchise's future.

Doncic became the first player in NBA history to lead the league in points (635), rebounds (208), assists (178) and steals (41) during a postseason. That was despite suffering a right knee sprain in the first round and a thoracic contusion in the Finals opener that required pregame pain-killing injections the rest of the series.

"It doesn't matter if I was hurt, how much was I hurt," Doncic said. "I was out there. I tried to play but I didn't do enough."

The injuries, however, have put Doncic's status to play for the Slovenian national team this summer in question. Slovenia will open an Olympic qualifying tournament in Greece on July 2.

"I don't want to talk about what's next, man," Doncic said. "I have some decisions to make. I'm just trying to get a little bit healthier."

Doncic, an MVP finalist who won the scoring title this season, has described his first Finals appearance as a learning experience. He cited the journey of the Celtics, a perennial contender that lost in the Finals two years ago, as a path the Mavs could emulate.

"For him at the age of 25 to get to the Finals, to be playing his basketball at the level that he's playing is, now it's just being consistent," Mavericks coach Jason Kidd said. "When you have one of the best players in the world, you should be always fighting for a championship."