Jennifer Garner's friends threw her an intimate birthday party on Sunday (16.04.17).

The '13 Going On 30' actress turned 45 on Monday (17.04.17), and friends of the brunette beauty organised a small and intimate celebratory bash at Little Beach House in Malibu just the day before she hit the milestone, which saw her and her close pals watch the sun set together.

Speaking about the party to E! News, a source said: ''Jen arrived with a small group around 6:30 p.m., just as the sun was starting to set.

''The ladies started out at the bar area, and once everyone arrived, they were moved to tables along the railing overlooking the ocean. The tables looked pretty with little votive candles, hydrangeas and roses.''

However, a handful of Jennifer's pals arrived earlier to help add the finishing touches to the site.

The source continued: ''A few of Jen's friends arrived before the party started to get everything set up.''

Reese Witherspoon was among the guests who attended the event, as well as Jennifer's manager and publicist, and the star's ''mom friends''.

The insider explained: ''Some of the girls were mom friends from school. Her manager and publicist were there as well.''

Although Jennifer filed for a divorce from her former partner Ben Affleck last week - almost three years after the couple separated - she is believed to have looked ''happy'' being surrounded by ''people closest to her''.

Speaking about the Texas-born star - who has Violet, 11, Seraphina, eight and Samuel, five, with the dark haired hunk - the source said: ''Jen looked so happy to be surrounded by the people closest to her. She had the best evening and was so gracious. She gave a little speech and thanked everyone for coming. Everyone went out of their way to make Jen feel special and be there for her. Her friends adore her and think the world of her.''