Britney Spears, who just kicked off her two-year residency in Las Vegas, revealed who she looks to for inspiration and included an ex-boyfriend.

Spears told USA Today on Dec. 27 that she "looks up to Beyoncé, what she did with her (surprise release) album was genius, really brilliant."

The mother of two also spoke about Miley Cyrus, with whom she collaborated with on the song SMS from the latter's newest album.

"She's cool, she's fun to be around," Spears said. "You know, she's got really good energy."

While she also listed Bruno Mars and New Zealand newcomer Lorde, Spears noted one more superstar - ex-boyfriend Justin Timberlake.

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"Bruno Mars is so different and fresh, and Justin Timberlake is, too," she said. "It's inspiring for me, and it makes people eager to listen to music, which helps everyone."

While Spears complemented several other stars, some came out to admire her at the debut show of Britney: Piece of Me at Planet Hollywood in Las Vegas on Friday. Cyrus, Selena Gomez and Katy Perry all cheered Spears on during the show, which received some rave reviews from critics.

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"Spears stomped into town with a 21-hit salute to her 15 years of dance confections the artfully melded spectacle with stagecraft," USA Today writer Marco della Cava wrote in his Saturday review.

MTV News writer Sophie Schillaci said: "Spears delivered on her signature style of larger-than-life production, blaring beats and rapid-fire dance moves, whirling through seven costume changes and even a couple of wig changes."

Tags: Britney Spears