Boxer Keith Thurman -- FLUTE TO KILL

What does boxing superstar Keith Thurman have in common with Ron Burgundy? They both LOVE the flute!

With the 26-year-old preparing for his big NBC "Fight Night" bout against Robert Guerrero, Keith told "Premier Boxing Champions" he's getting his mind right with some flute sessions.

"I find it really relaxing," Thurman said.

Apparently, the whole thing helps Keith get focused ... and it's worked so far -- the guy is 24-0 with 21 KOs.

And if the whole boxing thing doesn't work out, he could always get a job as a musical director at a spa.