The Mavericks have inched closer to their maiden NBA Championship with a 99-85 victory over the Miami Heat in Game Two of finals series at American Airlines Center in Dallas.

Dallas dominated from the outset and completely shut down Miami's power duo of Shaquille O'Neal and Dwyane Wade as they took a 2-0 series lead.

O'Neal had promised fans before the game he would fire up for the clash, but he took just five shots and finished with five points in a disappointing display.

Dirk Nowitzki was the star for the Mavs with a massive double-double, his 26 points and 16 rebounds marking a return to shooting form for the 213cm forward.

Nowitzki was supported well by Jerry Stackhouse who chipped in with 19 points off the bench, while Jason Terry (16pts, nine assists) and Josh Howard (15pts) also stepped up.

Wade battled hard to keep the Heat in the contest with 20 points, with Antoine Walker netting 20, but they were no match for a red-hot Dallas outfit.

The worrying thing for Miami is that Mavericks coach Avery Johnson conceded his team were nowhere near their best in their convincing win.

"We're not playing perfect basketball," Johnson said. "If you don't play perfect basketball and still can win another game like this - they score 80 and 85 points - we'll take it."

Johnson said the tactic of smothering O'Neal paid off and forced the Heat to try other avenues of getting to the basket, albeit unsuccessfully.

"We were really trying to double-team him quite a bit, even before he got the ball," he said.

"We're just trying to make them go other places sometimes."

The opening quarter was evenly balanced with the hosts taking a narrow one-point lead to the break, but the floodgates opened in the second.

Dallas stepped up the intensity with Howard dropping seven points in a 13-0 run that gave them a handy lead, before Stackhouse had the crowd on their feet with an attack that resulted in his team holding a 50-34 advantage at half-time.

The onslaught continued into the third period as the lead blew out to as many as 27 points, before the Heat clawed back some of the deficit in the final term.

But it was too little too late as Dallas held on for the victory and a massive psychological advantage heading into Game Three.