Admit it. You thought no free agent in his right mind would ever leave Dallas.

The AP reports that The Seattle SuperSonics, looking for a starting center after the departure of Patrick Ewing, signed Dallas Mavericks backup Calvin Booth to an offer sheet Tuesday.

The Mavericks have 15 days to match the Sonics' offer, but they are over the salary cap and would have to make a trade in order to clear enough room to keep Booth, a restricted free agent.

The Mavericks would be able to match any Seattle offer up to $4.5, but the Sonics have more than that amount in cap room because they let Ruben Patterson leave as a free agent and sign with the Portland Trail Blazers on Monday.