Over the summer the Kardashians enjoyed a well-documented family holiday to sunny St Barts, where Kylie decided to bring along her rapper boyfriend Tyga.

And in a sneak peek at an upcoming episode of Keeping Up With The Kardashians, Kendall can’t hide her anger as Kylie, 18, insists on spending most of her time with her other half.

“I was really looking forward to this trip to hang out with you,” she says disappointedly while Kylie, who moved into her own Calabasas mansion earlier this year, remains silent.

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Kendall admits she’s worried about Kylie

While in another scene, Kendall shares her concerns for her sister with dad Caitlyn.

The I Am Cait star bluntly asks the model: “What’s the deal with Kylie?”

The Victoria’s Secret beauty, 20, replies: “She doesn’t have her priorities straight and I tell everyone that.”

The sisters are seen getting ready for the ESPY Awards – where dad Cailtyn Jenner made her first post-transition red carpet appearance in July – and tensions run high when Kylie finds out Kendall wants to borrow a dress.

In classic sibling rivalry, Kylie won’t let her and the two soon begin to row.

“You’re just literally the biggest f****** b**** I’ve ever met,” Kendall fumes.

She goes on to say to Kylie’s dogs: “I’m sorry your mom is such a c***!”