Kyle Rover / StarTraks 1 / 15
Kyle Rover / StarTraks 1 / 15

Pre-birthday bash at the Chateau!

On Friday night, one day before her 43rd birthday, Jennifer Aniston was already in a festive mood.

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The "Horrible Bosses" actress turned up at Chateau Marmont in West Hollywood with love Justin Theroux and another male pal -- grabbing her favorite spot on the back patio.

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She and her man, 40, wore both clad in black with rocker-style leather jackets. "She looked great!" one onlooker tells Us, adding that she was "in a great mood ... smiling and glowing."

Arriving past nine, Aniston, Theroux and their pal drank wine as they chatted (and laughed!) for an hour and a half. Dating for nearly a year, the duo looked more in love than ever, according to the Chateau onlooker. "They touched each other alot! He had his hands in her hair at one point."

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They left before 11pm, hand-in-hand. No word yet on what Aniston and Theroux have planned for her big birthday weekend.