Formula One world champion Nico Rosberg hailed Mercedes team mate Lewis Hamilton as one of the greatest drivers of all time on Wednesday, and the Briton repaid the compliment by saying the German's title was well-deserved.
Hamilton sent congratulations in a message posted on Twitter after Rosberg had returned to his German birthplace in Wiesbaden.
"We said we'd be champions back then, now we both are!," said Hamilton, posting a picture of the two of them together as young go-karting team mates.
"Congratulations Nico, you did everything a champion needed to do. Well deserved," he added.
Rosberg, who lost out to Hamilton in the previous two years, made it third time lucky on Sunday when he clinched his maiden title with a second-place finish behind the triple world champion at the season finale in Abu Dhabi.
The childhood friends have been fierce rivals in Formula One and their body language was distinctly frosty immediately after Rosberg clinched the title.
There was minimal eye contact as they waited to go on the podium, where they did eventually shake hands in front of the crowd.
Hamilton had done his best to scupper Rosberg's chances by deliberately slowing the pace from the front, hoping to back Rosberg into a position where rival drivers could overtake the German in a last-ditch effort to overhaul his 12-point deficit.
"Lewis is one of the best of all time. He sets a high standard," the 31-year-old Rosberg told reporters.
"It will always be difficult between us. We are in the same team and race against each other for titles.
"It is virtually impossible to have a good relationship. We used to be best friends when we were young so at least we have this respect for each other. This helps somewhat," he added.
"I do not know how he feels at the moment but I know how I felt in 2014 and 2015."
Rosberg lost any hope of claiming the 2014 title with an engine problem at the final race of that season but, unlike Hamilton, has had no such reliability issues this year.
"For me it was difficult to stomach. In 2015 I lost to him again. It will now take some time for him to process this," Rosberg said.