Dallas ? Fresh out of a demoralizing film session, Jerry Stackhouse delivered Wednesday what could become the Dallas Mavericks’ rallying cry for the rest of the postseason:

“It’s about the fight.”

The Mavericks showed very little of it Tuesday in a game where the only emotional problem should’ve been too much enthusiasm.

Given the chance to get within a victory of their first trip to the NBA Finals, the Mavs instead played their worst game of the playoffs. The Phoenix Suns ran away with a 20-point victory, sending the Western Conference finals back to Dallas for Game 5 on Thursday night and forcing the Mavericks to wonder went wrong.

“Our body language as a group wasn’t there,” Stackhouse said. “I hate to say it, but maybe we got a little complacent.”

“It seemed like we just weren’t ready to play,” added Dirk Nowitzki, who shot 3-for-13 and scored fewer than 20 points for the first time since Feb. 21. “We were just going through the motions, and obviously, in the playoffs, you can’t do that, especially not in the Western Conference finals.”

The Dallas Mavericks' Dirk Nowitzki, left, and Jerry Stackhouse watch from the bench as their team falls, 106-86. The Mavs dropped Game 4 to the Suns on Tuesday in Phoenix.

Dallas coach Avery Johnson was glad to see his team leaders taking it so hard because that left less for him to bark at them about.

Still, he’s frustrated that his club has played “two really disappointing games this series out of four,” pointing also to dropping the opener at home.

Although the Suns only won that game by three, and it wasn’t decided until the closing seconds, Johnson came away furious over his team’s transition defense. The next day, he used that phrase seven times in a row when talking about what went wrong.

The buzzword this time was “attack,” as in going hard to the basket instead of settling for as many jumpers as they did in Game 4. The Mavericks misfired so often that their three lowest-scoring quarters of the series came over the second (18 points), third (21) and fourth (19) quarters.

“When we become a jump-shot-shooting team, we kind of play into their hands,” said guard Devin Harris, who has scored only 25 points since having 30 in the opener. “When we’re consistent going to the basket, we’re a tough team. … We always get something good in the lane.”

The Suns looked back to their fun, run-and-gun style in Game 4 after two sluggish outings that left two-time league MVP Steve Nash questioning his team’s aggressiveness.

Phoenix got an emotional boost Tuesday night with guard Raja Bell returning from a calf injury that had sidelined him since the opener. On Wednesday, Bell said he was “pretty sore and it’s a little stiff,” but was confident he’d play in Game 5.

Dallas’ Jason Terry hopes so.

“He’s definitely out there on one leg, so we do have to look at attacking (him) more,” Terry said. “But it’s their whole team. Regardless of who is out there in those Suns uniforms, we have to be in an attack mode. That’s what you’ll see of us in the next game.”

The series is now a best-of-three, with two games in Dallas. The Suns already have won there once and they took two games there in the second round last year, including the elimination game in overtime.

Plus, there’s the carry-over effect from Game 4.

“It’s going to be so important for us to find a way to make this game just like last night’s game,” Nash said.

It’s difficult to say which team is better equipped to handle the mental challenge over the next few days. Both have passed all their recent tests.

The Suns have been written off all season because of injuries, yet keep fighting. They overcame a 3-1 deficit to beat the Lakers in the first round, then outlasted the Clippers in seven games.

“We have a pretty special group of guys,” Bell said. “To have the chance to maybe take the upper hand in a series that means the NBA Finals, I think that should be enough motivation for anybody. That’s what we’ve got to preach the next 24 hours. The guys have to be ready to take it. It’s not going to be given to us.”

The Mavs eliminated the defending champion Spurs in a Game 7 in San Antonio after nearly blowing a 3-1 lead. Last year, Dallas lost its first two playoff games at home and rallied to beat Houston in that series in seven games, a comeback Johnson has referred to often during this series.

“The only good thing we can take out of Game 4 is that it doesn’t matter if we lose by 20, 30 or one point, it’s just one loss,” Nowitzki said. “It’s good to have a quick turnaround after a tough loss. You want to get out there and perform and forget about it.”