The Dallas Mavericks and Cleveland Cavaliers go into the season with championship aspirations. Both teams have given doubters good reason to be skeptical.

One team was a big disappointment by not coming close to making the NBA finals, and the one that did may have only gotten worse.

On Wednesday, Dirk Nowitzki and the Mavericks begin a regular season during which their title hopes will remain in question regardless of how well they perform, facing LeBron James and a Cavaliers squad which failed to improve during the offseason.

"You don't want to harp on what you've done wrong, you've got to find ways to move on," Nowitzki said. "But, still, the frustration - I won't forget."

The reigning league MVP is referring to Dallas' stunning first-round playoff loss to Golden State after having one of the best regular seasons in NBA history at 67-15. That record included three double-digit winning streaks - no team had ever done that - but it also may have caused the Mavericks to lose momentum or focus because they wrapped up the best record well before the playoffs began.

So whatever kind of win streaks or records Dallas achieves this season, questions will persist as to whether the team can carry that kind of play into the postseason. The Mavericks also closed the 2006 NBA finals by losing four straight to Miami.

"Some champion teams have to experience the agony of defeat to move forward," Mavs coach Avery Johnson said.

The Cavaliers hold out the same kind of hope after their run to the NBA finals last year in James' fourth season.

Still just 22 years old, James had a busy offseason - he hosted 'Saturday Night Live' and helped the U.S. win gold at the FIBA Americas tournament - but has gotten back to the business of pursuing a championship. He just wishes team management did the same.

Cleveland made no major acquisitions after being overmatched by San Antonio in a finals sweep, and two key members from that Eastern Conference title team - Anderson Varejao and Sasha Pavlovic - were missing throughout training camp.

"We didn't do any reshaping," James said candidly. "We didn't do any regrouping. You start to think a little bit, 'How are we going to continue to get better?'"

Both Varejao and Pavlovic have been holding out for better contracts and Cleveland's front office wasn't budging, and it appeared both players were are prepared to sit out the season. While that may still be the case with Varejao as he remains in Brazil, Pavlovic agreed to a three-year contract on Tuesday but is not expected to play in the opener.

Varejao averaged 6.8 points and 6.7 rebounds off the bench, but his biggest contributions came with his energy and defensive prowess. Pavlovic added 9.0 points per game and was one of Cleveland's best outside shooters, having made 40.5 percent from 3-point range.

"He's just very excited to have this behind him and be back in Cleveland where the fans really embrace him, and continue on the path they started last year and hopefully take it one step further," said Pavlovic's agent, Marc Cornstein.

James, picked in a recent poll of the league's general managers to supplant Nowitzki as MVP, joined Oscar Robertson last season as the only players to average at least 27.0 points, 6.0 rebounds and 6.0 assists in three straight years.

While James was fourth in the league with 27.3 points per game, Nowitzki's average dipped to 24.6 but his assists and shooting percentages were career highs.

Nowitzki clearly has the better supporting cast, but the Mavs' second-best weapon offensively won't be available Wednesday.

Swingman Josh Howard, who averaged a career-high 18.9 points last season, was suspended for the first two games for his role in an altercation with Sacramento's Brad Miller in a preseason contest.

Dallas still has plenty of capable scorers with Jason Terry and Jerry Stackhouse among others, and the roster hasn't changed much besides the additions of veteran Eddie Jones and second-round pick Nick Fazekas.

"When you have a team that's right there it's about being able to handle prosperity - winning 15 games in a row or getting to the finals - but it's also about handling adversity," Johnson said. "When you're not playing as well - when you have a losing streak or you're having a bad four or five games in a playoff series - how are you going to deal with it?"

While Dallas overcame an 0-4 start last season, Cleveland opened 7-2 en route to its second straight 50-win campaign and never went through a losing streak of more than three games until the finals.

James still is the centerpiece and Zydrunas Ilgauskas is a key figure in the middle, but the Cavs may need their backcourt to step up to stay a title contender in an Eastern Conference in which many teams made notable offseason moves to improve.

Cleveland is counting on second-year point guard Daniel Gibson to carry over his impressive playoff performance, and hopes veteran Larry Hughes can stay healthy while producing on a more consistent basis.

"There will be more pressure on us, because now there's only one more step up to win a championship," Ilgauskas said. "Other than winning one, the year will be considered a disappointment. But it's a nice place to be, finally, after all these years. We don't want to just make the playoffs anymore or just advance past the first round."

Dallas swept the two-game series with Cleveland last season despite James averaging 35.0 points, and has lost only two of the last 13 meetings.

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