Britney Spears Gets Support From Siblings, Kids

The Britney Spears Circus tour is getting rave reviews from those closest to the singer - her siblings, cousins, her ex-husand and their two sons.

"Britney's whole family was there, her parents Jamie and Lynn Spears, [sister] Jamie Lynn Spears, [brother] Bryan Spears, his wife Graciella Sanchez, her cousins [including] Laura Lynn [Covington], friends from Kentwood – everyone thought it was a fantastic show and she just nailed it," a source close to Spears tells People.

The source was referring to the Louisiana native's kickoff concert Tuesday night at the New Orleans Arena, the first stop on her 36-show tour.

Added the source: "They all thought Britney was so amazing – her energy, her spirit."

Sean Preston, Britney and Jayden James in the Magic Kingdom.

Also in attendance: the singer's sons Sean Preston, 3, and Jayden James, 2, and their dad Kevin Federline. "He was there to support her as well," says the source, adding that the boys stayed backstage as "it's just too loud for them."

The "spectacular" (to quote her manager Larry Rudolph) Cirque du Soleil-style show also got the thumbs-up from fans, and marks the pop star's first tour in five years and comes after a year of getting her life back together.

After a brief stop in the Magic Kingdom Theme Park in Lake Buena Vista, Fla., Spears hit Atlanta last night, with 10 shows on the East Coast to follow.

Click to enlarge photos from her Atlanta show ...