Kyrie Irving is confident the Dallas Mavericks can be regular championship contenders after their NBA Finals loss to the Boston Celtics came as a "bitter" ending to a "really positive journey".

Jayson Tatum delivered a magnificent performance in Game 5 with 31 points, eight rebounds and 11 assists, as the Celtics capped a dominant season by cruising to a 106-88 victory over the Mavericks on Monday to capture their first league championship since 2008.

It was a difficult night for Irving at TD Garden. Boston's All-Star forward and Finals MVP Jaylen Brown compiled 21 points, eight rebounds and six assists and played lock-down defence on the Mavericks star, who was held to under 39 per cent shooting in three of Dallas' four losses.

Irving, who spent two seasons with Boston before signing with the Brooklyn Nets in 2019, went just 5 of 16 from the field while managing 15 points, the third time in the series he produced 16 points or fewer.

But Irving was looking at the positives despite the 4-1 series loss and hopes Dallas will be back to go one better in the years ahead.

"We answered a lot of questions this year on what we were capable of doing and now it is just about being consistent," Irving said, per ESPN.

"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 are competing for championships. 

"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."

After Dallas substituted its starters in the closing stages, Irving and Doncic exchanged an embrace and a few words on the sideline as the final seconds of the Celtics' victory ticked away.

"We said, 'We'll fight together next season, and we are just going to believe'," revealed Doncic.

Doncic battled injuries during the postseason and it remains uncertain if he will be able to represent Slovenia at the Olympic Games.

"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.

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

With Doncic on the team, Mavericks coach Jason Kidd is optimistic there will be more NBA Finals appearances to come for Dallas.

He said: "For [Doncic] at the age of 25 to get to the Finals, to be playing his basketball at the level that he's playing...

"Now it's just being consistent. When you have one of the best players in the world, you should be always fighting for a championship."