Arguably the best power forward in NBA history, Tim Duncan is now channeling his power towards another sport after retiring from professional basketball last year.

Jason Echols, Duncan's long-time mixed martial arts trainer, recently shared a tweet of the Big Fundamental working on his kickboxing fundamentals:

It's great to see the five-time NBA champ keeping himself fit post-retirement through another one of his passions. Or, maybe Timmy D's just preparing to land a swift roundhouse to anybody out there that calls his style of basketball boring. Either way, he best not put any “Spurs” on his heels to really wreck the faces of his detractors.