Justin Timberlake calls Justin Bieber his "lil' bro".
The 'SexyBack' hitmaker shared some "kind words" with the 21-year-old singer backstage at the 'Ellen DeGeneres' show on Thursday (12.11.15) and has urged him to "keep up the good work".
Bieber tweeted to Timberlake: "Good seeing you and thanks for the kind words. Means a lot."
His 34-year-old pal replied: "You too. Keep up the good work, lil' bro."
Bieber also took to Instagram to share a selfie of himself with Jennifer Aniston, who was another surprise guest on the 2,000th episode of Ellen's show.
The 'Sorry' hitmaker didn't share any screen time with the two stars on the programme, but he has made frequent appearances in the past and this week the talk show host is celebrating Justin Bieber week.
And earlier this week, the Canadian pop star admitted to the presenter that he would consider reconciling with former girlfriend Selena Gomez.
Asked if they'd ever get back together, he said: "Maybe? We have a lot of history together and I am sure it could possibly happen. I think we are both just on our own journeys and figuring ourselves out and I think maybe once we figure ourselves out we can come back and make an awesome duo or she finds someone awesome and I'll find someone awesome. I just want her to be happy."