Jaylen Brown said the Boston Celtics had learned from past mistakes after they took another step towards clinching the NBA championship with Wednesday's Game 3 victory over the Dallas Mavericks.

Brown had 30 points, eight rebounds and eight assists as the Celtics took a 3-0 lead in the series, holding off a late Dallas push to claim a 106-99 win.

They could now capture a record-breaking 18th NBA crown on Friday, when they are again on the road for Game 4 at American Airlines Center.

The Celtics were beaten NBA finalists against the Golden State Warriors two years ago and have also lost two Eastern Conference finals series in the last five seasons.

Brown thinks experiencing those near misses has made them stronger, saying: "Experience is the best teacher. 

"All year long we've been hearing about the Celtics in the past, for the last six to eight months, all we've been hearing is all the different shortcomings we've had in the past.

"This is a new team, you know what I mean? We've learned from those experiences. In these moments, you can see that we learned from it. We stepped up to the plate, and we found a way to win."

None of the previous 156 teams to face a 3-0 deficit have rallied to win an NBA playoff series, in any round.

Dallas gave themselves a chance of making a series of it when a 22-2 spurt pulled them within one point with three minutes and 37 seconds left.

However, a Brown putback was followed by a Derrick White 3-pointer and a Tatum dunk as the Celtics rediscovered their composure to pull clear once more.

Tatum is refusing to take his eye off the ball despite Boston now having four chances to clinch the title, saying: "Last year, when we were down 0-3 in the conference finals, we really felt like we were going to come back.

"We almost did. You know, we were my sprained ankle away from having a real shot, so we are not relaxing or anything like that. 

"You know, we're not even focusing on winning or Friday or whatever. However long it takes, that's our motto. That's what it's going to take, and nobody is trying to relax at all."