Double world champion Fernando Alonso will retire from Formula One at the end of the season, he has announced.
The 37-year-old Spaniard is competing in his 17th F1 season and his fifth with McLaren, and has been widely tipped to race in the Indianapolis 500 next year as he attempts to win the Triple Crown of Motorsport.
Alonso, a double Monaco Grand Prix winner, won the Le Mans 24 Hours on his debut with Toyota in June this year and is currently ninth in the F1 drivers' championship standings.
Alonso said in a statement: "After 17 wonderful years in this amazing sport, it's time for me to make a change and move on.
"I have enjoyed every single minute of those incredible seasons and I cannot thank enough the people who have contributed to make them all so special.
"There are still several grands prix to go this season, and I will take part in them with more commitment and passion than ever.
"Let's see what the future brings; new exciting challenges are around the corner. I'm having one of the happiest times ever in my life but I need to go on exploring new adventures."
Alonso's current team, McLaren confirmed the news on their official website.
And McLaren Chief Executive Zak Brown said: "There is a time for everyone to make a change and Fernando has decided the end of this season to be his.
"We respect his decision, even if we believe he is in the finest form of his career."
Alonso was F1 champion in 2005 and 2006 while he was with Renault, with his first championship ending a five-year dominance by Michael Schumacher and Ferrari.
He went on to join McLaren in 2007 before returning to Renault in 2008. Alonso then made the switch to Ferrari two years later and stayed with the Italian marque for four years, before rejoining McLaren once again.
However, Alonso left the door open to a return to F1 - strongly hinting that this could be a hiatus rather than a retirement.
He added: "I have built so many great relationships with many fantastic people at McLaren, and they have given me the opportunity to broaden my horizons and race in other categories. I feel I am a more complete driver now than ever."