Heat check for Western Conference rivals

The Los Angeles Lakers have taken the position that they will not trade Shaquille O'Neal to the rival Dallas Mavericks unless they receive Dirk Nowitzki as part of the exchange, team sources told ESPN.com on Tuesday.

O'Neal demanded a trade Friday in the wake of the Lakers' loss to Detroit in the NBA Finals and coach Phil Jackson's departure. Dallas is believed to be his No. 1 choice for a new home. Trade talks between the two clubs began Tuesday, but Lakers sources told ESPN.com that L.A. insists on Nowitzki as the staple of any package from the Mavericks.

Mavericks sources, meanwhile, maintain that Nowitzki is likely off-limits and Mavs owner Mark Cuban told the Dallas Morning News Wednesday night that he would not include Nowitzki in any deal for Shaq.

Even if the Mavericks could convince the Lakers to accept a package that leads with point guard Steve Nash, instead of Nowitzki, Nash would have to agree to join L.A. in a sign-and-trade because he's a free agent as of July 1.

Whether either team changes its position likely will depend on how forcefully O'Neal pressures the Lakers to move him, and how tantalized the Mavericks become if the possibility of acquiring Shaq becomes more real.

Amid growing belief around the league that the Lakers are serious about honoring Shaq's trade request -- with the Clippers emerging as a possible trade partner -- O'Neal can try to influence where he lands because of an opt-out in his contract next season. Although the Lakers technically have the freedom to deal O'Neal anywhere, O'Neal does have some of the same leverage Tracy McGrady possessed in pushing for a trade to the Houston Rockets. That's because any team willing to give up enough in a trade to take on Shaq's $27.7 million salary for next season must also have confidence it will be able to re-sign him in the summer of 2005, or else it will be paying a hefty price to risk having O'Neal for only one season.

Marc Stein is the senior NBA writer for ESPN.com. To e-mail him, click here. Also, click here to send a question for possible use on ESPNEWS.