After he gathered his senses, Morales, a five-time world champion, thanked his dedicated legion of fans and told them this was his last fight in the United States.
He said he would fight one more time in Mexico to say "bye-bye."
"Now that's the way you put a legend into retirement," said Hopkins, who is also an executive in Golden Boy Promotions, which has Garcia under contract. "When you're a young champion like Danny and you're fighting a veteran champion like Morales, you're supposed to make a statement and take care of that just the way he did.
"I'm 47 years old. If some young guy would have slayed me a decade ago the way Danny slayed Morales, maybe I wouldn't still be out there in the mix.
"Morales is over. How can he go to some promoter 6 months from now and say put me on your card? They would literally be indicted for assassination."
It was an amazing 24-hour swing for Garcia.
The holder of the WBC, WBA and The Ring belts went to bed Friday night saying he was not going to fight Morales, who reportedly failed a pair of recent random drug tests for a banned substance.
Morales, who did not make weight in the first fight, said he got clenbuterol, a weight-loss aid that can also be a masking agent for performance enhancing drugs, in his system from eating tainted meat in Mexico.
With suspicions from the first fight, Team Garcia insisted on random testing for the rematch.
Garcia was prepared to call off the biggest fight of his career, even though Morales had clean urine in a third test.
But when the family gathered for one final discussion Saturday morning, Garcia's mother, Maritza, reminded her son this was what he had dreamed of his whole career.
She didn't want him to let Morales ruin it. Besides, as she reminded Danny, he had already beaten Morales the first time when they thought he might be dirty.
In addition to the mind-clearing conversation, Garcia said, "I want to thank my mom for the left hand. My whole family's lefthanded, and that's what I got him with."
At just about midnight, when Morales' corner dashed into the ring to halt the assault unleashed on their disoriented fighter, Garcia had unequivocally destroyed a legend in front of 11,112 fans in attendance and a national television audience on Showtime Championship Boxing.
Swift had emphatically arrived.
"I'm only 24 years old," Garcia said. "I'm not even in my prime yet. I'm maturing as a fighter and a man.
"All the hard work, everything I've sacrificed to do this is paying off. You haven't seen the best of Danny Garcia yet."
That's impressive because in less than a year, Garcia (25-0) has captured a title and twice defended it.
In his fight before the Morales rematch, Garcia had stretched out the highly regarded Amir Khan in five rounds to retain his WBC belt and gain the WBA and The Ring titles.
Sitting with the media in front of the podium as Garcia spoke, six-division world champion and future Hall of Fame fighter Oscar De La Hoya, who started Golden Boy Promotions 5 years before he retired in 2001, was as pleased as Hopkins.
"When we signed [Garcia in 2007], we obviously saw potential, but not just in the ring," De La Hoya said. "We knew he had boxing skills, but we saw him as a guy who could potentially cross over to the general masses of sports fans, not just the hard-core boxing audience.
"He just headlined the opening of a magnificent arena on a night that was historical in Brooklyn. The sky is really the limit for Danny now, especially after that devastating knockout."
Thinking back on what he saw Garcia do to Morales, Hopkins intimated that his fellow Philadelphian may have accomplished something none of his opponents could do in the ring - convince Hopkins it's finally OK to hang up the gloves for good.
"When you're the old lion, you always want to find a successor to take over your reign," said Hopkins, who proudly represented Philadelphia as the middleweight champion for a record 20 consecutive title defenses spanning a decade. "I've been carrying it on my shoulders for a long time.
"You don't want to leave your throne without a successor. When you've got a successor like Garcia, I can rest now.
"Garcia did what a young guy is supposed to do as far the networks are concerned, the media is concerned, the boxing business is concerned - to get the credibility and become a star."
Contact John Smallwood at email@example.com.