Michael Bublé always knew Adele would be the "biggest singer in the world".Michael Bublé and Adele wanted to record a song together - but the "timing wasn't right".The Canadian crooner claims he has been friendly with the British singing sensation for years, even before she shot to worldwide fame. He has recalled how the pair were eager to get into the recording studio, but their plans for a duet were dashed due to conflicting schedules."I am a huge fan of Adele. It's funny because we used to email each other and talk about doing something together before her debut album 19 came out, but the timing wasn't right," he told British magazine Closer. "I can remember writing to her, saying, 'I can't wait for you to be the biggest singer in the world.' She wrote back very simple and sweet. I was really happy to see it happen for her - she has an incredible talent."Michael has friends all over the entertainment industry. He has recorded a song with Reese Witherspoon for his new album To Be Loved and also keeps in contact with One Direction.The singer admires the British boy band for remaining grounded despite their incredible success."They're really nice kids and it seems that even with all of this craziness that's surrounded them they've somehow managed to stay really normal and fun," he explained. "It's [all] absolutely nuts, but I think they have good parents. When I talk to Niall, he'll still say, 'I can't believe this is happening to me,' and I love that. I get excited for them and their potential and wonder how it's going to go for them."