So now Lewis Hamilton is playing nice.

Hamilton tweeted congratulations to Mercedes teammate Nico Rosberg for winning his first Formula One season championship this week, just a few days after Rosberg won the title in the season's final race at Abu Dhabi.

Hamilton tweeted a photo of the two drivers when they were much younger and still close friends.

"We said we'd be champions back then, now we both are! Congratulations Nico, you did everything a champion needed to do. Well deserved," Hamilton tweeted.

The tweet took the high road in a strained relationship. The two drivers came up through the karting circuits but became fierce rivals in recent years as they dueled for F1 championships with Mercedes. Hamilton beat Rosberg to titles in 2014-2015 and stormed back this season to push the chase to the final race. The drivers constantly needled each other in the media, and Hamilton won the final four races of the season before Rosberg won the title by finishing second in Abu Dhabi — after Hamilton ignored his team's orders to back off.

Rosberg responded to Hamilton's congratulations with a note of thanks.

"thanks for your words. it is unbelievable that what we were talking about on that night at our holiday in Greece has actually come true," Rosberg tweeted.