Alvaro Morata joined Chelsea against the wishes of Zinedine Zidane as he did not want to spend another season among the Real Madrid substitutes.
The Spain international signed for the Premier League champions in July for a reported club-record fee of £58million, despite having only returned to Madrid the year before.
Morata made 43 appearances in all competitions last season but only 19 of those came as a starter, with Karim Benzema preferred as first choice.
The 24-year-old says his desire to "grow up" and force his way into the Spain starting line-up for next year's World Cup prompted his decision to turn his back on Madrid for the second time in his career.
"Zidane wanted me to stay and I was happy in Madrid. But I couldn't stay to be a substitute," Morata, who joined Juventus in 2015 on a permanent deal, told the Daily Mail.
"You reach a point that you need to play, to grow up, to escape a comfort zone. It's about being comfortable. I don't want that. I am ambitious and hungry to succeed.
"For Spain, the more I play, the more goals I score, the more chance I have of making the World Cup and starting games."