San Francisco Frontiers - Hamilton leads affectionate tributes to retiring Vettel

Seven-time champion Hamilton, who made his debut alongside the 35-year-old German in 2007 and was his greatest rival for many years, said it had been an honour to have raced and befriended him.

"Seb, it's been an honour to call you a competitor and an ever greater honour to call you my friend," said Hamilton in a post on Twitter. "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."

Later in a paddock interview, he added: "He is one of the few who stood for much more than himself. He used his voice and helped support.

"He has taken the knee from the start and he takes his own journey and he has fought for the things he believes in and for the greater good.

"And I am delighted to have been here and raced alongside with him and I am sad at today's news, but I know he will do things beyond this."

Vettel's protege and friend Mick Schumacher, son of seven-time champion Michael, said his compatriot had been an important part of his own career.

"I'm so sad that you're leaving, but at the same time excited for you and this new chapter of your life. You've been and still are such an important person to me and I'm thankful for our friendship."

- 'Great role model' -

Ferrari's Carlos Sainz told reporters ahead of this weekend's Hungarian Grand Prix how generous Vettel had been to him when he was the simulator driver at Red Bull during his halcyon days, winning four drivers' championships.

"From the beginning, he's always been a great role model. When I was his simulator driver, at Red Bull, I could see how professional he was – and he was my role model -- and he always had time to give advice.

"He has been a great ambassador for the sport and for the younger generation and everyone in F1 loves him for his personality and his life as a human being. We will miss him, but I hope to see him back in the paddock to help us with the future of the sport."

His Ferrari team-mate Charles Leclerc, who worked with Vettel at the Italian team, said: "He's definitely a legend. I have grown as a driver and as a person with him and through him.

"I feel that we have a special connection. He has always been super nice, a simple and very nice guy."

Another former team-mate, at Red Bull, Daniel Ricciardo said: "It is sad, of course, as we are losing legend and for me personally – I spent time alongside him, which was for sure a privilege. So I'm sad and happy for him to start chapter two of his life.

Valtteri Bottas, another long-time rival, said he had great respect for him and for his work on behalf of drivers' safety. "And he used his platform for all the right things," he said. "He was always fair and a very nice person to get to know."

World champion and series leader Max Verstappen of Red Bull praised him for his achievements and his four titles, adding that his work at Red Bull had paved the way for his own successes.

"Of course, we all know what he did at Red Bull and there are lots of stories about him from back in the day," he said.

"For me, it is nice to be there with an experienced team that has been fighting for titles thanks to him."

D.Parker--SFF