One more big fourth quarter probably should do it for the Dallas Mavericks.

A final sprint is all that’s needed for the best closers of this postseason to join other resilient champions while also embarrassing the Heat, an added benefit for Miami’s many detractors.

With another victory, Dallas would win its first NBA Finals, completing an impressive postseason run and elevating Dirk Nowitzki among the game’s all-time greats. LeBron James figures to benefit most if Miami overcomes a three-games-to-two deficit in the best-of-seven series. That’s what he’s seeking to validate his move from Cleveland to Miami in the offseason, but James hasn’t embraced the moment as much as Nowitzki.

Throughout the playoffs, Nowitzki has been more than a perennial all-star. He’s no longer simply the greatest deep-shooting 7-footer ever.

Nowitzki has become a momentum-changing offensive force. He has been as unstoppable as Hakeem Olajuwon was while leading the Houston Rockets to consecutive titles in the 1993-94 and 1994-95 seasons.

Nowitzki has shot more consistently than Kobe Bryant did when the Los Angeles Lakers won their two most recent titles in 2008-09 and 2009-10. The focus of opponents’ plans, Nowitzki has attracted attention similar to that which Shaquille O’Neal received when the Lakers won three straight championships from 2000 through 2002.

Nowitzki doesn’t have a remarkable low-post game, unique athleticism or power. For him, it’s all about the best fadeaway jump shot in NBA history, an incredible shooting touch and smarts, which are also good things to possess.

Dallas leads the playoffs in late-game mettle because Nowitzki scores a lot in the fourth. His ability to make shots down the stretch was impressive against Portland, Los Angeles and Oklahoma City in the Western Conference playoffs.

None of them is Miami’s equal on defense. Based on statistics, reputation or any other comparison imaginable, the Heat is as good as it gets defensively. Still, that hasn’t helped much.

Dallas is ahead as the Finals shift back to Miami for Game 6 on Sunday. If necessary, Game 7 will be played Tuesday on the Heat’s home court.

Back in 2005-06, Nowitzki led the Mavericks to a two-games-to-none Finals lead against the Heat. After building a 13-point cushion late in Game 3, the Mavericks collapsed, lost four straight and the series.

A team’s best player should shoulder blame for such an epic meltdown, and Nowitzki deservedly received a lot. More would come.

The following season, Dallas established a franchise record with 67 victories and Nowitzki was named the league’s most valuable player. The Mavericks, seeded first in the West, then lost to the eighth-seeded Golden State Warriors in the first round as Nowitzki struggled.

Those setbacks follow Nowitzki. Regardless of other accomplishments, they remain on his career ledger. He owns them.

Winning a championship, however, minimizes earlier failures. Defeating the league’s most star-heavy lineup adds to the degree of difficulty. Doing it with a Jordan-esque performance would definitely put Nowitzki on the right side of history.

Nowitzki, 32, already has Hall of Fame credentials, but a title provides the final stamp of greatness. It’s how the best of the best judge one another.

Hall of Famers Elgin Baylor, Charles Barkley and Patrick Ewing finished their careers without winning a title. Obviously, they were great players, and each came close to helping their teams reach the top.

But that absence of a title matters when comparing them to players who have similar stats and wear championship jewelry.

This is where James thus far has fallen short.

In his eighth NBA season, James is seeking his first championship. The anti-James crowd offers this as proof he’s more hype than substance and carries the “non-clutch gene.”

James is only 26 years old. He took the Cavaliers as far as they could go without having another star on their roster and then left to team with Dwyane Wade, who already earned his championship cred, and Chris Bosh in hopes of building something great.

Problem is, in the Finals, James has faded in what Magic Johnson refers to as “winning time.” James went missing on offense for long stretches — especially in the final quarters — as the Heat lost Games 4 and 5.

Although he continued to facilitate others with great passes, James needed to score more points. That’s what great players do.

The expectation is that less-talented teammates will miss shots in the biggest moments. Stars are paid to win games. Wade aggressively took charge in the losses. James, a two-time league MVP, needed to act similarly.

James had a triple-double in Game 5 (17 points, 10 rebounds and 10 assists). He also scored just two points in the fourth quarter, and that was after the outcome had been decided.

In the first five games, Nowitzki has scored 52 points in the fourth quarters combined. James has produced 11. Those numbers can’t be ignored with a championship at stake.

After Scottie Pippen’s recent ill-advised Michael Jordan-James comparison, James has been crushed on Twitter for his disappearing act. Jordan and James are alike only in their uniqueness.

Wade is more like Jordan in that he’s a prolific scorer. On offense, James is the best ballhandler and passer of his size since Magic. On defense, he’s a great on-ball defender capable of guarding multiple positions as Pippen once did so well.

James is not Jordan. That’s just not the way he plays the game. But facing elimination and the possibility of squandering everything it has worked for, the Heat needs James to be a lot more than he has been, or at least closer to who Nowitzki is right now.