KSI is gonna wanna see this ...
Here's Logan Paul beating the dog snot out of his sparring partner during a recent training session -- and ending it all with a CLEAN knockdown shot to the face!!!
TMZ Sports got our hands on the footage of a recent workout for Paul's August 25 boxing match against KSI ... a fight that some say could get more viewers than Mayweather vs. McGregor.
The YouTube star is clearly taking the fight seriously ... he's been training like a maniac and looks pretty solid in this video.