Harry Styles says he got help from Ed Sheeran when he was picking the tracks for his debut solo album.
"I played him a few songs after the album was finished," Harry told the Radio 1 Breakfast Show.
"He didn't say that he didn't like any but he did like one song that isn't on the album."
Ignoring the advice of one of the most successful singer-songwriters might not be a good idea, but Harry says he still decided to leave it off the album.
"He [Ed] is really good - he's one of the most talented dudes I know," he said.
The first play of Harry's new single, Sign Of The Times, will take place during the Radio 1 Breakfast Show on Friday and Harry will also be co-hosting with Nick Grimshaw.
It's the track he says he is "most proud" of writing.
"I feel like I've been hibernating for so long now and you hear it [the album] in the safety of the studio and now it's time to give birth," he says.
Most of the album was written in Jamaica where he spent two months.
"For a while I was stressing about what it [the album] was going to be.
"We did 50 songs and ideas in Jamaica and that's including little ideas."
One of the songs on the album he wrote in the days before One Direction, admitting it's "a few years" old.
His debut has become his "favourite album to listen to".
Harry says: "I think if you put out something that you don't stand behind and really love, then if it doesn't go well then you could regret not doing what you wanted to do.
"Whereas if nothing happens with it, I love it."
When it comes to his love life, Harry says it's been a while since he's met someone special.
"I haven't dated in a long time really because I went away to do the movie [Dunkirk], then did the album.
For a while, he says, he used to research potential dates online, before meeting up in person.
"Then I said I'm not going to do that anymore, it's impossible to go in without a perception of someone and you've never met them and I started feeling like that was wrong and weird."
Hear the full co-host and world premiere of Harry's debut single at 8am on Friday 7 April on the Radio 1 Breakfast Show.