Singer Brian Joo thanked his mentor and friend,�Tiger JK.

The singer shared the above photo via his official Twitter page on January 25th and wrote, "Thank you so much for the lyrics, and for your rap feature in the song. The reaction to the teaser has been awesome, thanks to you, hyung."

Tiger JK then re-tweeted this comment, and cheered on his fellow junior singer.

The two recently collaborated on "Taking Leave Of You", a new song from Brian's new album, 'ReBorn - Part 1'. It is rare to see Tiger JK make a feature for other artists, but it looks like he made an exception for an exceptional artist such as Brian Joo.

The two have been friends since Brian debuted with Fly to the Sky, and grew close after realizing that they had a lot in common. They have maintained their good relationship to this day.

A source close to Brian remarked, "Brian asked Tiger JK to make a feature, and he was more than happy to do so."

In related news, Brian recently released his new album ReBorn Part 1 at midnight (KST) on January 26th.

Source & Image: Brian's Twitter