LOOK: Christian Lee back at United MMA, celebrates with brother Adrian on brown belt promotion

ONE Championship two-division king Christian Lee has been spotted back on the mats of his family-owned United MMA in Hawaii, United States.

The lightweight and welterweight king, who has been out of action since his world title victory over Kiamrian Abbasov in November last year, is expected to return to competition early next year.

He has stayed pretty much off the grid after his sister's passing on Boxing Day last year, focusing on family throughout the tough period.

However, based on a recent Instagram post from the youngest of the Lee siblings, Adrian, it could be safe to say that the record-breaking MMA world champion has been working on his craft.

The 17-year-old uploaded a picture of him beside his brother, 'The Warrior,' after his BJJ brown belt promotion recently.

In the caption, he wrote:

"I just got recently promoted to brown, Thank you to my coach and training partners for helping me reach this level of grappling and jiu-jitsu!"

'The gentle art' has been one of the strongest aspects of the Lees MMA arsenal, and their thirst for improvement has helped them rise to the top of the charts at a rapid pace.

Victoria, at her time of passing, was a purple belt. Christian and Angela are both black belts.

It remains unclear whether or not the eldest sibling, atomweight queen Angela, will return to action per ONE Championship Chairman and CEO Chatri Sityodtong.

The lifelong martial artist, however, revealed to South China Morning Post that Christian will likely return to the ONE fold next year.