MIAMI (NBA.com exclusive) --  It would be easy to look at Steve Nash's 30 points and eight assists and think that's the main reason the Suns defeated Miami 104-96 on Tuesday at American Airlines Arena.

Sure, Nash was outstanding. His 17-point third quarter was vintage. There was a pair of 3-pointers, a couple of fadeaway baseline jumpers, and a few defense-wrecking drives for layups.

"He came out in that third quarter and put on a clinic running that high screen-and-roll," said Suns forward Grant Hill, who recorded his third double-double with 10 points and 12 rebounds.

But what won this game for Phoenix, pushing its record to 4-0 for only the third time in franchise history, was defense, specifically zone defense, a tactic the Suns used for the first time this season. And they used it to contain Heat superstar guard Dwyane Wade.

"I thought our zone did a great job against Wade," Phoenix coach Alvin Gentry said. "We held him out of the paint."

Wade (23 points, nine rebounds, seven assists) toyed with a triple-double, but he was only 2-for-6 from the field in the fourth for eight points.

"The zone changed our rhythm," Heat coach Erik Spoelstra said. "We didn't have a lot of answers for that."

Phoenix made its first statement in the third. It cut its eight-point halftime deficit to just one at 57-56 just two minutes into the quarter. Nash had eight points and an assist in that brief stretch.

"I just felt like I was too passive [in the first half], and I was thinking instead of going," he said.

Nash's success triggered a trend of blistering shooting. The Suns shot 60.5 percent in the third and ended the game shooting 50.6. Miami (3-1) had held its previous three opponents to 41 percent or worse.

Phoenix made its follow-up statement when it took an 87-84 lead on Jared Dudley's three-point play. It marked the Suns' first lead since 36-33 in the second. The Heat, which was outscored 29-15 in the fourth, never recovered. And Phoenix, which blocked six shots over the final 12 minutes, owes much of that to its defense, specifically its zone defense.

Miami, which did so many things well in the first half, struggled mightily in the fourth. The Suns' zone defense held the Heat to 21.7 percent shooting (5-for-23 from the field, including 1-for-10 on 3-pointers) in the period as Miami seemed content to fire up jumpers instead of working on solving the zone.

Some in Miami are already starting to question Spoelstra's trend of keeping second-year forward Michael Beasley (12 points, four rebounds) on the bench down the stretch in close games in favor of veteran Udonis Haslem. Although Haslem posted his third double-double with 10 points, 13 rebounds) some want to see Beasley's offensive diversity at the end of games.

"We were just trying to get some athleticism in there to speed it up, and [forward] Dorell [Wright] is another guy that can put the ball on the floor against the zone," Spoelstra said.

This was the start of a five-game Eastern Conference road swing for Phoenix, a tough stretch considering each opponent -- Miami, Orlando, Boston, Washington and Philadelphia -- figures to be in the playoffs.

"It's an important win for us," Nash said.

Notes

? Phoenix can match its all-time best start at 5-0 with a victory Wednesday at Orlando. ... Phoenix swingman Leandro Barbosa missed the game with a sore right wrist. He's listed as day-to-day. ... Miami guard Daequan Cook missed his second consecutive game due to a bruised right shoulder. He's listed as day-to-day. ... Hill missed a dunk over Haslem that would have rated as one of the most memorable plays of the season.

? Nash became Phoenix's all-time leader in 3-pointers made at 801, surpassing Suns assistant coach Dan Majerle (800). ... Tuesday marked just the sixth time coach Gentry has coached Amar'e Stoudemire in a game. The Suns are 6-0 on such occasions. Gentry took over Feb. 16, two games before Stoudemire went out with a detached retina in his right eye, which caused him to miss the season's final 29 games ...

? Haslem became the first player in franchise history to record three consecutive double-doubles off the bench. He tied a franchise record with his third consecutive game with a double-digit rebounding total off the bench. Center Vladimir Stepania did it in November 2002. ... Miami forward Quentin Richardson had a double-double with 18 points and 10 rebounds.