Swift performs at Reese Witherspoon's 40th birthday party

Actress Reese Witherspoon celebrated her 40th birthday on Saturday with a private performance by Taylor Swift and a duet with Keith Urban.
The "Legally Blonde" star marked the age milestone on Tuesday, but her family helped her get into the party spirit a little early by throwing a big bash in Hollywood this weekend, with a string of celebrity friends in attendance.
Guests at the event, held at the Warwick, included Kate Hudson, Matthew McConaughey, Robert Downey, Jr, Courteney Cox, Tobey Maguire, Jason Bateman, and Jennifer Aniston and her husband Justin Theroux, reported Hollywood Life.
Nicole Kidman was also spotted at the party, where her husband Keith was part of the night's entertainment, alongside surprise performer Taylor.

Witherspoon, who arrived with husband Jim Toth, shared her excitement as she headed to the bash in a Snapchat video with her mother Betty, who was featured nodding as the actress asked, "Are you gonna get crazy on the dance floor, Mum?". She captioned the brief clip, "Crazy on the dance floor? #BirthdayWeekend #MomsInTown".
Meanwhile, her friend Hudson also used social media to document the night's celebrations, including the moment when Swift was introduced to the stage for her unexpected appearance, singing an acoustic version of "Shake It Off".
Witherspoon, who wore a sparkly silver dress, also got in on the fun by hopping onstage to join country star Keith, who played guitar for a rendition of Lynyrd Skynyrd's "Sweet Home Alabama", which featured on the soundtrack to her 2002 romantic comedy of the same name.