OneRepublic's lead singer Ryan Tedder has worked with an impressive catalogue of stars including Beyonce and Leona Lewis and now he's turned his attentions to Adele.
The songwriter and producer, who penned Beyonce's hit Halo and Leona's recent single Happy, says he's been trying to get together with Adele since before the Grammys and describes her as "one of his favourite artists in the world".
The pair have been working on a follow-up to her debut 19 and Ryan says it's important to him that Adele still retains her own sound.
He told Newsbeat: "I'm letting Adele be Adele.
"19, that album was so absolutely mind-blowing to me, so simple and beautiful that I don't want myself as a fan to interfere with her sound.
"Yesterday the song we did was very much Adele - it was 10% Ryan, 90% Adele."
He says he told the singer: "I don't want to put you through the Ryan Tedder machine where you end up with a song that sounds as much like Ryan Tedder as it does Adele."
Ryan's past list of collaborations ranges from James Morrison and Kelly Clarkson to Paul Oakenfold and he shows no signs of being pigeon-holed in any particular genre.
Having so many contacts in the music industry, he's never short of offers to work with other artists but this year he wants to keep it to a "relatively short list" of five or six people.
Those so far on his radar include Ne-Yo, the Noisettes. Lupe Fiasco, Imogen Heap and in the new year, Rihanna.
He admits he's been trying to synchronise schedules with the Umbrella singer for about a year and a half now and wants to get her pushing the boundaries.
He said: "She's in a darker musical place right now… she's got enough of those songs on Rated R to last for a while.
"I can do stuff dark musically, haunting kind of thing, but I want to have her do something vocally that she's never done before."
Another UK act?
It's hard to pin him down on his future direction as the one thing he's sure about is that he wants to "blend all the genres together".
He's planning on working with more bands, as well as building on his dance material and revealed that "a pretty substantial UK act" is also in the pipeline - though he can't say which one for now.
So with songs like Beyonce's Halo (which he modestly dubs the tune that "worked out rather well") under his belt, which song is he most proud of?
That would have to be Leona's Happy - which although it wasn't as big as Bleeding Love - is one that he's lyrically most proud of.
He said: "That's the kind of song that when I'm 50 and my kids are like: 'What kind of music did you do?' I'll play them Happy and a few other songs.
"I'm more interested in the songs that 10, 20 years from now, people are requesting - whether it's at their wedding or whether it's at their funeral or graduation.
"The kind of songs that attach themselves to people's lives because they live on long after I'm dead."
Tedder's band OneRepublic rose to prominence with hit single Apologize from 2007 debut album Dreaming Out Loud, and in November they released follow-up Waking Up.
The band came along way before the songwriting and it was only because he had to pay the bills after pretty much paying for the band's instruments on his credit card that Ryan started penning lyrics for other people at all.
He admitted the idea of writing for other people wasn't very appealling at the beginning.
He said: "You have to spend the rest of your life watching everybody else sing your songs, which for me was too difficult to bear."
So for him, the band will always take priority: "OneRepublic was always the focus and it still is.
"Having your own song, having OneRepublic on the radio or in people's homes, that to me is the best because that's what started it all.
"First and foremost I'm the lead singer of OneRepublic, second I'm a writer/producer."