Antoine Griezmann has told Atletico Madrid fans in a video message that he will leave the club at the end of the season.
The French striker did not reveal where he will play next season but it is widely assumed he will join Spanish champions Barcelona, who have courted the 28-year-old World Cup winner for some time.
Greizmann famously rejected the Catalan club last year in a documentary before penning a new contract to tie him at Atletico until 2023.
Griezmann posted the video on Atletico's Twitter account, saying he had informed manager Diego Simeone and chief executive Miguel Angel Gil Marin of his decision to leave following Saturday's final game of the season away to Levante.
"After speaking to Simeone and Miguel Angel and the club hierarchy I wanted to immediately tell you, the Atletico fans who have always given me a lot of love that I have taken the decision to leave, to see other things, to have other challenges," he said.
"The truth is it has been difficult to arrive to this point but I feel it's what I need to do. I want to thank you for all the support you have given me in these five years, where I won my first trophies."
Griezmann rejected overtures to join Barca last June, documenting his internal struggles about whether to make the move in a documentary called The Decision, which was produced by Barcelona defender Gerard Pique's production company Kosmos Studios.
After rejecting a move to Camp Nou, Griezmann penned a new five-year contract at Atletico that initially raised his release clause to €200 million (Dh824m). However, several Spanish media reports say that figure will drop to €120 million on July 1.
Griezmann's inevitable departure will be keenly felt by the club who were already reeling from two other recent high-profile defections.
France defender Lucas Hernandez has agreed to join Bayern Munich after the German club paid his €80m release clause and long-serving captain and club stalwart Diego Godin will join Inter Milan on a free transfer this summer.
Griezmann, who joined Atletico from Real Sociedad for around €30m in 2014, has been the team's top scorer in his five seasons at the club, netting more than 130 goals in over 250 games.
His arrival coincided with a huge upturn in Atletico's fortunes in which they have emerged as serious title challengers to Barca and Real Madrid and are regular Champions League qualifiers.
Griezmann scored twice in Atletico's 3-0 Europa League final victory against Marseille in 2018 and collected a runners-up medal after Atletico lost the 2016 Champions League final to city rivals Real Madrid. Griezmann was named as the third best player in the world at that year's Ballon d'Or awards.
"I've had some incredible moments which I'll always remember, I'll always hold Atletico fans in my heart, it's never easy to make a decision like this," added Griezmann.
"Many thanks for everything, I have really enjoyed myself in the last five years, I've given everything on the pitch and I've always tried to be a good person.
"I have tried to give lots of joy to the fans at the Wanda Metropolitano and to our fans at away games, many thanks from my heart and until next time."
Widely regarded as one of the best strikers in the world, the thought of Griezmann lining up alongside Lionel Messi and Luis Suarez at Barca next season should send shockwaves throughout Spain and Europe.
Should Griezmann make the move to Catalonia, it is likely to spell the end of Philippe Coutinho's time at the club.
The Brazilian, who joined from Liverpool in January 2018 for a fee that could rise to £142 million, has failed to win over Barca fans and has often been the subject of boos and whistles from the stands.
Atletico will finish second in La Liga behind Barcelona irrespective of the result against Levante as Simeone's side hold a seven-point lead over third-placed Real Madrid.