With production slated to begin in two months, "Ocean's Thirteen" filmmakers are worried that the third installment of the uber-cool heist franchise will be sorely missing key player Brad Pitt.

According to the report, Pitt -- whom you'll recall plays Danny Ocean's (George Clooney) super smooth, card-hustling BFF Rusty Ryan -- has not yet signed his contract to appear in the flick, contrary to earlier assumptions that the original main characters were definitely returning.


Matt Damon, Brad Pitt, and George Clooney in "Ocean's Twelve"


Pitt has been bunkering down in Namibia recently with expectant baby's momma Angelina Jolie, who the tabs speculate will give birth any week now. Producers are said to be worried that Pitt, once a father, will neglect his professional duties and -- gasp! -- opt instead to spend time with his family.

Digital Spy brings us the news from The Sun, who squeezed the scoop from an unidentified "source," if that gives you any indication of its reliability:

"Best friend George Clooney, who plays Danny Ocean and is one of the producers on the new film, is said to be very worried about the situation.

A source told The Sun: 'Brad has not been able to confirm 100 per cent that he will be available - and that's making George very anxious.'"

"Ocean's Thirteen" has a release date of June 8, 2007. The rest of the original cast is set to return (minus Julia Roberts), and will include new additions Ellen Barkin and Al Pacino; helmer Steven Soderbergh will reprise his role behind the camera.