Could Lindsay Lohan celebrate her 21st birthday sober?

It's hard to think it's possible, but with Lohan in rehab since May 28 and her birthday July 2, it's likely -- particularly from a publicity point of view.

Despite ads and billboards (including a prominent one across from Rio) indicating otherwise, Lohan's 21st at PURE (Caesars Palace) has been canceled as of yesterday.

Lohan may keep her fee (rumored at $1 million) but will still have a post-21st bash for PURE.

Meanwhile, we expect PURE to milk advertising their club alongside Lohan's name until that party happens.