EXCLUSIVE

Baltimore Ravens lineman Bryant McKinnie took a HUGE gamble on the eve on the 2011 NFL lockout ... but his gamble didn't pay off ... and now he's gotta come up with $4 million QUICK ... or else.

Back when McKinnie was a member of the Minnesota Vikings ... dude must have had a feeling a lockout was on the horizon ... because in February 2011, he took out a $4 million personal loan with Pro Player Funding ... which specialized in "lockout loans" for NFL guys looking to cover their asses during the impending pay freeze.

According to court docs obtained by TMZ ... the loan was VERY high risk ... with high interest rates and a clause that allowed PPF to call in the entire amount due if Bryant missed ONE payment.

And that's exactly what happened in August 2011 ... right after the lockout ended and Bryant was CUT from his team.

But there seems to be an explanation ... according to the docs, McKinnie had directed his paychecks to go directly from the Vikings to PPF. But when Bryant was fired and the paychecks stopped, he never arranged for PPF to get its payments ... and he missed his August bill.

PPF instantly went to the court and obtained a judgment against McKinnie ... ordering the NFL star to pay back his entire loan ... plus interest ... totaling $4.3 million.

During the lockout, several NFL players spoke out against loans of this sort claiming they weren't in the best interest of the players ... and now McKinnie seems to be living proof.