Antonio Conte emerged as favourite to take over the vacant Italian national team manager's job after he resigned as Juventus coach on Tuesday.
Conte, 44, steered Juventus to a third consecutive title last season, the first time the club had achieved the feat since a five-season title run in the 1930s.
His shock announcement came in a video posted on the club's official website.
Dressed in a black-and-white striped Juventus shirt, Conte told the website he felt time had caught up with him at the club and that the time was right to go.
"I have decided to terminate my contract with Juventus," he said.
"I have matured with time and my feelings led me to make this choice. It may be more difficult to keep winning with Juventus.
"An enormous thank you for what you have given to me as a player and as a coach. I have always been close to you. I want to say that the journey taken in recent years has been historic."
The feeling was reciprocated by club chairman Andrea Agnelli, who wote on the site: "Dear Antonio, you have been a great leader and this news saddens me greatly.
"Three years together have led us to write history with three consecutive titles and two Italian cups."
He added: "Antonio, thank you for everything. Til the end."
The managerial merry-go-round has seen Conte emerge as a front-runner to succeed Cesare Prandelli as Italian national manager, after Prandelli's post-World Cup resignation and subsequent appointment in charge of Turkish side Galatasary.
Ironically, former Manchester City boss Roberto Mancini, recently released by Galatasaray, and ex-AC Milan manager Massimiliano Allegri were already being linked with the Juventus job.
Conte had already hinted he could quit the Serie A giants if they failed to invest in players during the summer break, ahead of a fresh assault on the Champions League.
After winning the title, Conte, speaking in the third person, said: "If Antonio decides to take another path, then he will do so with the greatest respect for the club and the players."
Conte's time in charge of Juve had not been without its controversial moments, as in the summer of 2013, he was caught up in a corruption row after he was charged with failing to report attempted match-fixing during his time with his previous club Siena.
He protested his innocence but was banned for 10 months, reduced on appeal to a a four-month touchline ban, which saw him miss the first half of last seasaon.
Conte, who captained the club during his playing career which stretched over more than 500 games and included five league titles, also led Juve to a record points haul of 102 points as they won their 30th official league title last season.