Entertainment Tonight.

Britney Spears found an economical way to celebrate two major occasions over the weekend when she combined her birthday and end-of-tour party into one big bash.

The pop susperstar tweeted a picture of herself on Friday, blowing out the candles of her 30th birthday cake one day before the last show of her Femme Fatale tour.

MORE: Britney Spears Reveals "Grueling" Rehearsal Routine

Her birthday party was a belated one as she was born on December 2.

After her final performance in Puerto Rico, Britney tweeted her thanks to those who worked hard behind the scenes.

"To every single INCREDIBLE person on my crew -- none of this would of been possible without you," Britney wrote. "I'm gonna miss u!"

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