Red Bull boss Christian Horner says he was not surprised when Sebastian Vettel left the team for Ferrari.
Vettel left after failing to win a single race in 2014, despite winning four consecutive Drivers' Championship titles Red Bull.
Horner said: "And I think Ferrari were courting him quite hard and around Spa/Monza was the time he made the decision to do something different next year."
"By the time he got to Singapore you could see he was a different person. He was more relaxed and you could see he had made his mind up, but events had to unfold through Fernando actually leaving Ferrari. So, no, it wasn't a great surprise in the end.
"The timing was right for Sebastian. He'd had a great run with us. He'd been with Red Bull since 12 years of age.
"He's won four World Championships, 39 Grands Prix, 45 pole positions and I think he felt: 'I've reached 27 years of age. I don't want to end my career without having driven for Ferrari and I have a great opportunity to go there.'
"The lure of Ferrari for any driver is immensely powerful."