"The Match" is starting off hot ... with Patrick Mahomes opening up a barely healed wound, clowning his own golf teammate Josh Allen over the Bills' BRUTAL overtime playoff loss to the Chiefs!

The two QBs are back on the green for the first time since the AFC divisional round ... taking on Tom Brady and Aaron Rodgers in a celebrity golf match.

But, before the round began, the four superstar signal-callers were asked a series of questions from fans on social media... one question being, "Josh's biggest fear?"

Mahomes' (super cold) response ... "A coin toss."

OUCH!!! And, Allen must have felt it too 'cause his reaction was priceless!!!

Of course, KC beat Buffalo during their January playoff game, with a trip to the AFC Championship game on the line, scoring 25 points in the last 2 minutes of regulation, forcing OT.

The Chiefs won the coin toss ... and the rest is history. KC advanced, but ended up losing to the Bengals.

Another fan asked Allen if it's true he throws up before every game.

Allen confessed ... saying, "I do throw up before every game."

And, with all the pressure of The Match, is it possible he might blow chunks before he tees off?

"If I start thinking about it, I get a little queasy."

There's more -- Brady dropped an "F" bomb right off the bat ... with the hot mic picking it up.

Allen also hit a spectator in the hand on the second hole ... so yeah, this is nothing short of entertaining.