Jenson Button has announced he will not be racing in Formula One next season.
The 36-year-old, who has participated in every season since 2000, will take a year out of the sport next term and will be replaced by McLaren's highly-rated reserve driver Stoffel Vandoorne.
Button, the 2009 world champion, made the announcement flanked by McLaren chairman Ron Dennis in the team's motorhome on the eve of the Italian Grand Prix - he later posted a video on Instagram for his fans.
"I can tell you now that I do have a two-year contract starting next year with McLaren-Honda, and next year I will be an ambassador for this team," Button said.
"I will work with this team in every way I can to make it a better team for the future. I will train my arse off like you have never seen before and I will also do a lot of races to make sure everything is on the right track.
"I will also be doing a lot of stuff that I haven't done for 17 years. I will be living on my schedule, spend more time with my friends and more importantly my family who I haven't seen properly in 17 years. That is something I am really excited about.
"There are many things I want to do that I haven't been able to do because of the Formula One schedule. You are not just a racing driver when you drive in F1 - this is your life - and I definitely need a break from that in 2017.
"So, 2017 will be that and in 2018 the team have an option on me to race for McLaren-Honda which is pretty awesome."
Button has made nearly 300 grands prix starts in a career which has spanned 17 seasons, yielded 15 wins and 50 podiums.
Vandoorne, who made his grand prix debut in Bahrain earlier this season as a replacement for Alonso following his shunt at the season opener in Australia, will take Button's seat.
"First of all, I want to express my gratitude to everyone at McLaren-Honda, and especially Ron, for showing faith in me," said Vandoorne.
"I've signed loads of autographs in my career, but, when I inked my signature on my McLaren-Honda contract today, it's safe to say I had an exceptionally special feeling as I picked up my pen to do so.
"It's an enormous honour to become a McLaren-Honda race driver, and I promise to work as hard as any Formula One driver ever has before."