There are actually two notable deadlines Thursday in the NBA.
One is the buzzer sounding at midnight that signals the end of the current collective bargaining agreement and sends the league into the uncertainty of a lockout.
But Thursday is also the last day for free agents-to-be such as the Denver Nuggets' Nene and the Dallas Mavericks' Tyson Chandler to sign contract extensions that would keep the two big men off the free-agent market ... whenever free agency starts after the forthcoming lockout.
Yet in both cases, no extension is anticipated Thursday.
Nene has already notified the Nuggets that he will opt out of the final year of his contract to become a free agent, according to the Denver Post.
The Nuggets have been engaged in extension dialogue with Nene for months, dating to late in the regular season, but sources with knowledge of the talks told ESPN.com that Denver would have to make an offer worth more than $13 million annually to convince Nene to forego the opportunity to become, along with Chandler and New Orleans' David West, one of the three most coveted free agents in the league.
As for Chandler, sources told ESPN.com that there has been minimal conversation between the Mavericks and their defensive anchor about an extension since Dallas won the first championship in franchise history on June 12.
As badly as the Mavericks want the vocal Chandler back to reprise his role as the most impactful frontcourt sidekick Dirk Nowitzki has ever played with, team officials are apparently determined to see exactly how restrictive the new salary-cap rules are after the lockout before trying to re-sign the Team USA big man.
The risk there is that Chandler, like Nene, is sure to attract interest from numerous teams, which means that Dallas will have to deal with serious competition to keep him, as opposed to the past two weeks since the championship when only the Mavs could negotiate with him.
Besides big-spending rivals such as Miami and New York that sources say would love to try to steal Chandler from the Mavs if they had any financial flexibility, sources likewise indicate that at least two teams projected to have some salary-cap space in the NBA's new frontier -- Sacramento and Toronto -- are already making plans to go hard after Chandler when they are finally granted that opportunity.
The good news for Dallas is that Chandler, by all accounts, wants to stay in Big D and would presumably have little interest at this point in playing for any team that isn't in the championship mix. The teams with the lowest projected payrolls for next season (Sacramento, Indiana, New Jersey, Washington, Los Angeles Clippers and Toronto) are all lottery teams.
The 28-year-old seemed to tip his hand about how much he wants to return during the Mavericks' post-parade celebration at American Airlines Center on June 16, when joked LeBron James-style about how he expects Dallas to go on and win "two, three, four, five" championships.
Yet Chandler made it clear in a recent interview with ESPN 103.3's Ben and Skin Show that there are no guarantees he'll be back no matter how successful he was in a debut season with the Mavs that prompted Nowitzki, on numerous occasions, to label him team MVP for the season because of the lift he provided defensively.
"Honestly, at this point, I'll let my agent and the management hash everything out," Chandler said during the recent Ben and Skin interview. "I try not to get involved with it, because then it becomes personal. I honestly try to stay out of it as much as possible and then at the last minute, when I need to make decisions, I'll come in and me and my agent will sit down."
Chandler finished third in the league last season in NBA Defensive Player of the Year voting after averaging 10.1 points and 9.4 boards while playing in 74 of 82 games despite concerns about his injury history.
"Tyson Chandler changed our season on a lot of levels," Mavs coach Rick Carlisle said shortly after the season. "It wasn't just his play. It was his enthusiasm, his energy. He just brought a certain exuberance to our locker room and he was always a guy who was talking about accountability. He was talking about it, preaching it and it got other guys in the locker room on board with keeping each other accountable.
"Because, if you don't have a team that polices itself, you can't win an NBA championship."
Said Nowitzki: "Tyson, to me, turned everything around. ... Looking back now, that was almost [like] a key signing. His positive energy, his defense, I think, is what turned this whole thing around. Every big game down the stretch, we did it with defense.
"Obviously we'd love to get a deal done with Tyson and keep him here in the long run. I've never played with a center as athletic, as quick and able to cover as much ground and play with his energy. He was a pleasure to play with."
The trade to acquire Chandler from Charlotte last summer was the fourth for Chandler in the space of three seasons, although two of those deals -- one from New Orleans to Oklahoma City, another from Charlotte to Toronto -- broke down after they were agreed to.
He's one of six unrestricted free agents in Dallas, along with J.J. Barea, Caron Butler, Brian Cardinal, DeShawn Stevenson and Peja Stojakovic.
"In an ideal world, we keep it intact and make another run,'' Mavs president of basketball operations Donnie Nelson said earlier this month. "But ... none of us knows what the market is going to be like. So it's just, 'We're in a holding pattern.'"
Senior writer Marc Stein covers the NBA for ESPN.com.