Red Sox's Michael Chavis Flips Off Rays' Kevin Kiermaier After Insane Catch

Tampa Bay Rays center fielder Kevin Kiermaier ROBBED Red Sox rookie Jonathan Arauz of his first career hit with a miraculous catch on Monday ... and you know who was super-pissed about it??

Sox first baseman Michael Chavis -- who straight-up gave Kiermaier a one-finger salute after making the highlight play!!

The hilarious interaction was caught on camera ... when Kiermaier leaped to catch Arauz's deep shot to center field in the 2nd inning.

Chavis made his frustrations known by getting KK's attention from the dugout ... just to give him a solid middle finger!!

So, why is Chavis so mad?? If Kiermaier hadn't come up with the ball, 22-year-old Arauz would have notched his first MLB hit ... but of course, that didn't happen.

It all ended up okay in the end for Arauz -- he finished the game with 3 hits as the Red Sox fell to the Rays, 8-7.