David Stern has added another negotiating session to the two already scheduled with NBA players next week, and says there will be more beyond those.

Even that might not be enough to prevent a work stoppage.

The NBA Commissioner acknowledged Tuesday it will be "a challenge" to reach a deal for a new collective bargaining agreement before the current one expires in a month.

"The question is whether the owners and the players will be bold enough to do what has to be done here to keep this sport on the track that it is on now, which is straight up," Stern said during his annual news conference before Game 1 of the NBA finals.

Owners are seeking major financial changes to the deal that expires June 30. Without an agreement, the owners could then lock out the players.

The sides already planned to sit down twice when the series moves to Dallas, and Stern said Tuesday groups from both negotiating committees will be in Miami on Wednesday for what he called a "full-blown" bargaining session.

"We told the players and the owners to bring their negotiating talents to South Beach," Stern said, poking fun at the line LeBron James used when he announced he was leaving Cleveland as a free agent last summer.

Both sides insist they want to avoid a situation similar to the NFL's, which is currently being carried out through the court system — though the players did file a charge against the NBA with the National Labor Relations Board last week for unfair bargaining practices.

So Stern said the key is continued meetings before the deadline, some in small groups and others with more voices in the room.

"I know that both sides will make their best offers before the lockout, because if they don't, then there's going to be a lockout that would be destructive to our business from the owners' perspective and the players' perspective," Stern said. "So that's why we've scheduled these sessions, and we'll schedule more, because we want to face this issue."

Stern said the league learned of the union's NLRB charge while on the way to a negotiating session last week, where the players offered some unspecified new ideas. He said the league was not concerned by the complaint, adding "that's a part of the challenge, really, whether we're going to be bold enough to negotiate as opposed to posture."

Players have balked at the owners' desire for a hard salary cap system to replace the current one that allows for certain exceptions. Stern didn't deny that a hard cap could force the Heat to have to break up their trio of James, Dwyane Wade and Chris Bosh to conform to new rules.

The league also seeks to slash player salary costs by nearly $800 million annually, along with reductions in the length of contracts and the amount for which they can be guaranteed.

Deputy commissioner Adam Silver, the lead negotiator for the league, says costs have risen faster than revenues during this CBA, which was ratified in 2005.

"The built-in increases of our contracts are much higher than inflation and the growth in our business," Silver said. "For example, the three key players on the Heat all have 10½ percent per year increases built into their deals for next year, at a point when revenues in our business are growing somewhere around 3 percent. It's a broken system."

Players quickly rejected the owners' initial proposal for a new deal in February 2010 and the league finally made a second one at the end of last month that didn't interest the union. The players have made just one counterproposal last summer, but Stern said the sides continue to exchange ideas.

He said they aren't near the point where they could extend the June 30 deadline, and that "everyone knows that offers get worse, not better" in a work stoppage.

"As David said, I think it would be a mistake for both sides if we do not put our best proposals forward before that deadline, because it is a very real deadline," Silver said. "And while we've incurred some damage already, it will move to a new level once we're in a work stoppage, if that were to occur."