Britney Spears Serenaded by Fiancé on Private Jet As She Celebrates 40th Birthday

Britney Spears kicked off her 40th birthday celebrations in style on Wednesday, when she boarded a private jet for a vacation with her fiancé Sam Asghari.

The pop superstar, whose big day falls on Thursday, took to Instagram to share photos of herself sporting Daisy Dukes and red knee-high boots as she shared kisses and hugs with her partner while standing aboard the jet.

Captioning the images, the singer wrote: "Oh the precious joy today !!! Me and my fiancé are so excited to be going away .... as you can see I'm not 800 pounds like the paps have me in pics ... I've been working out and it's real ... whatever !!!! God thank you for being able to go out of the country !!!! I am blessed !!!!"

Model and actor Asghari, 27, also posted one of the shots on his own Instagram account, adding the caption: "I call you Lioness because I admire your relentless strength, I'm inspired by your beautiful heart, I celebrate your smile that lights up my world... Everyday is your birthday my queen."

In an apparent reference to this being Spears' first birthday since the recent dissolution of her 13-year conservatorship, Asghari added: "Happy 1st birthday to my wife #dec2nd @britneyspears."

Answering the speculation that his closing sentence had sparked, Asghari, who proposed to Spears in September, added of his wife-to-be in the comments section: "I also been calling her wife since day 1."

Soon after take-off, Asghari was seen singing "Happy Birthday" to the star as he presented her with a layered B-shaped cake that was decorated with red and pink roses.

Spears, who appeared to be shooting the footage, was heard gushing off camera: "Oh my God, it's a beautiful B!"

While presenting the "Gimme More" singer with a glass vase of colorful roses, Asghari quipped: "I'm gonna take credit for this, because it's an amazing cake."

"Baby this is hot," said Louisiana native Spears, as Iranian-born Asghari settled into an upholstered seat opposite her. "This is so nice."

While the lovebirds have yet to reveal their destination of choice, Asghari returned to Instagram a handful of hours later to share footage of a night-time firework display over a beach, adding the caption: "Happy birthday."

As well as celebrating her milestone birthday, Spears is also enjoying a newfound freedom, after a judge ruled on November 12 that her conservatorship should end.

Under the arrangement—which was implemented in 2008 amid mental health concerns for the star—Spears' personal and financial decisions were taken out of her hands. Her father, Jamie Spears, was suspended from the conservatorship in September.

In an explosive court testimony back in June, the star alleged that she was made to perform, take medication and wear a contraceptive device against her will.

Britney Spears, who has two sons—Sean Preston, 16, and Jayden James, 15—with her ex-husband, Kevin Federline, has expressed a desire to have another child.

Britney Spears and Sam Asghari
Pop star Britney Spears (R) boarded a private jet for a vacation with her fiancé Sam Asghari on Wednesday, as she kicked off celebrations for her 40th birthday. Britney Spears/Instagram