Heat's O'Neal talking with Celtics, Mavericks, Nuggets

Former All-Star center Jermaine O'Neal is in discussions with Boston, Dallas and Denver, a source familiar with the talks told SI.com. Multiple sources stress that no deal for O'Neal is considered imminent with each team evaluating what O'Neal, 31, can still offer. Sources say any offer for O'Neal will be for two seasons at close to the $5.8 million mid-level exception.

Once one of the NBA's most dominant big men, age and knee injuries have robbed O'Neal of his athleticism and explosiveness the last few seasons. In 70 games with the Heat last season O'Neal averaged 13.6 points and 6.9 rebounds.

After failing to acquire a draft pick to use on a big man in June's draft, the Nuggets have been actively seeking a big body to supplement Nene, Kenyon Martin and Chris Andersen in the frontcourt. Dallas is in the market for a new center with Brendan Haywood (free agent) and Erick Dampier (non-guaranteed contract) possibly not returning next season.

Boston is desperate to add size. Rasheed Wallace has said he plans to retire while Kendrick Perkins is out until at least January with a knee injury. The Celtics are interested in Bulls center Brad Miller and have worked out former No. 1 overall pick Kwame Brown. It's also possible they could get involved in discussions with Shaquille O'Neal, who has been contacted by Atlanta and Dallas.