Lewis Hamilton said he has "lost an ally" as he paid tribute to Sebastian Vettel, who will retire at the end of the Formula One season.
Vettel, now racing for Aston Martin, confirmed on Thursday that he would be calling time on his illustrious career.
The German is a four-time world champion, winning all of those titles in consecutive seasons between 2010 and 2013.
That success proceeded Hamilton's dominance of F1, with the Briton winning six of his seven world titles from 2014 onwards.
Two years Vettel's senior, Hamilton is sad to see the 35-year-old call it a day.
"My first feeling is that it is sad he is stopping," Hamilton told reporters ahead of the Hungarian Grand Prix.
"The journey I have experienced in this sport, often feeling relatively lonely, Seb has been one of the few people that has made it not feel that way. He stood by me through a lot of things.
"We talk about legends, I don't really like that title but he is one of the greatest people we have seen in this sport and we need more people like him. I am sad because I have lost an ally."
Seb, it’s been an honour to call you a competitor and an ever greater honour to call you my friend. Leaving this sport better than you found it is always the goal. I have no doubt that whatever comes next for you will be exciting, meaningful, and rewarding. Love you, man. pic.twitter.com/eHVmOpov2m— Lewis Hamilton (@LewisHamilton) July 28, 2022
Only Hamilton (103) and F1 great Michael Schumacher (91) have won more races in the format than Vettel (53).
Hamilton also believes Vettel has used his platform for good, saying: "There's no lack of bravery in Sebastian. He has been one of the very, very few drivers in racing history that has stood for much more than himself.
"He's used his voice in things that I've fought for and stood by me, he's taken the knee, he's gone on his own journey and stood on the grid and fought for things that he believed in, and for the greater good.
"I think he's just a really beautiful human being and I'm really grateful to have been here in a time that he was racing.
"Watching his World Championships was impressive. I'm sad to have arrived today and seen the news, but I know whatever he goes and does beyond this is going to be even better."
Hamilton's sentiment was echoed by Fernando Alonso, who competed closely with Vettel during the latter's dominant streak.
The Spaniard said: "Not the news that I want. There were some rumours last year that maybe he stops, but this year it came true.
"An amazing driver, a legend of our sport. I spent so much time and battles with him over my career with him. So I will miss him, and not only as a driver, I think he has very strong values and is a very good human being. I wish him the best and we will miss him."