Sia has praised Britney Spears's vocals on a track they recently worked on together.
The pair worked together earlier this summer on a new track for the 'Circus' singer's eighth studio album, which is expected to be released later this year.
The Australian singer-songwriter wrote to Spears earlier today (August 20) to praise her performance on the song.
She tweeted: "@britneyspears your vocal on this tune is outstanding. WERK!"
Spears tweeted fans about her session with Sia last month, describing the co-written song as "special".
"Had an AMAZING writing session today with the beautiful and talented @Sia," she said. "We wrote such a special song together :)," she posted to her followers.
The 32-year-old has teased an announcement for September 17 with a countdown clock on her official website. It is expected that she will announce her new single.
She has worked with the likes of William Orbit, Danja, Jean Baptiste and Hit-Boy on the record, with 'Scream & Shout' collaborator will.i.am serving as executive producer.
Meanwhile, UK producer Naughty Boy - who has teamed up with Orbit on Spears's new collection - said that the star is one of the few artists who can "change pop culture with what she does", adding: "Those are the things that excite me. What can you do with popular culture?"