High flying Serial Dating Ace TAYLOR SWIFT moving in on ultimate “kill”  to notch on fuselage—JUSTIN BIEBER.

 DATE-’em-and-dump-’em Taylor Swift is zeroing in on Justin Bieber – and it’s wrecking her friendship with BFF Selena Gomez, say sources.

Following a two-year relationship, Bieber, 18, split with Selena, 20, just over a month ago. Afterward, a distraught Selena poured out her heart to Taylor and later told a pal: “It’s so hard to trust girls. I’m lucky to have her.”

But Taylor – who’s blazed through a dozen boyfriends in the past four years – was swift to swoop in on the suddenly unattached Biebs.

“Taylor feels Justin is fair game now,” revealed an insider. “She’s had a crush on him for years.”

And that has Selena singing a differ­ent tune about Taylor.

“She’s heartbroken at the thought of the two of them getting together,” said the insider. “She’s quizzed Taylor about her intentions to­ward Justin, and Taylor says, ‘He’s just a friend – you know that!’”

But actions speak louder than words, and the insider divulged that Taylor and Justin “phone and text each other at least four times a day, and they never even mention Selena.

“Taylor says that as a superstar himself, Justin is the one person who knows what her life is like. She says Justin just ‘gets her,’ and she finds that incredibly romantic.”

Bieber has a longtime bond with the 23-year-old blonde beauty. He occasionally pops up as a guest act at her concerts and has called her “a sweet girl.” But no one’s really expecting them to have a long-running relationship.

Said the pal: “Taylor’s the most fickle girl in the world!”