The liver shot didn't appear overly hard -- Tank was a bit out of position when he threw the punch -- but seemingly caught Ryan on the liver. After a few second delay, Ryan dropped to a knee, and winced in pain, as referee Thomas Taylor began to count.

Garcia remained on one knee for the entire 10-count ... and just like that, the fight, 5 years in the making, was over.

24-year-old Garcia got off to a nice start ... winning the first round.

However, the fight turned in the second when 28-year-old Tank, ducking under a left, caught Garcia with a beautiful left hook/uppercut that dropped Ryan, sending him to the canvas. He returned to his feet quickly.

From that moment on, save for a few flashes, Tank was in control of the fight.

Earlier in the week, Davis said he was going to stop Garcia in the 7th and that's what he did.

After the fight was over, Tank and Ryan embraced in the ring and squashed any beef they might've had, shaking hands ... after years of going back and forth with trash talk.

In what was the biggest fight of the year, the celebs were out in full force ... with everyone from Mark Wahlberg to Floyd Mayweather and Mike Tyson watching from their ringside seats.

Chief Keef even walked Gervonta to the ring, performing as Davis made his way to the squared circle.

Last week, Oscar De La Hoya, Ryan's promoter, told us the winner of the fight was set to become the face of boxing.