Spence was on his feet when the fight was stopped, but Crawford dropped him in the second round and twice during the seventh round. No prior opponent had sent Spence to the canvas in any of his first 28 professional fights.

It was a legendary, masterful performance by Crawford, who fought exclusively out of a southpaw stance, completely controlled the action and proved pretty early that he is stronger and better than the courageous Spence in every way. Crawford has knocked out all eight of his opponents since he moved into the welterweight division early in 2018.

All three judges – Tim Cheatham, David Sutherland and Steve Weisfeld – had Crawford ahead 79-70 entering the ninth round.

Crawford, 35, became boxing’s first fully unified welterweight champion of the four-belt era. The three-division champion from Omaha, Nebraska native retained his WBO 147-pound championship and won the IBF, WBA and WBC belts from Spence (28-1, 22 KOs).

Crawford (40-0, 31 KOs) also earned the distinction as the sport’s first male undisputed champion in two divisions since the IBF, WBA, WBC and WBO belts were all recognized. He was the undisputed 140-pound champion prior to moving up to welterweight five years ago.

“It means everything because of who I took the belts from,” Crawford told Showtime’s Jim Gray in the ring. “They tried to blackball me. They kept me out. They talked bad about me. They said I wasn’t good enough and I couldn’t beat these welterweights. I just kept my head to the sky and kept praying to God that I would get the opportunity to show the world how great Terence Crawford is. Tonight, I believe I showed how great I am.”

Spence has 30 days to exercise his contractual right to an immediate rematch, but Crawford can dictate the weight limit for their second bout. Spence told BoxingScene.com on Wednesday that he wanted this to be his last fight at the welterweight limit because it takes too much out of him physically to squeeze down to 147 pounds.

“We gotta do it again,” Spence said to Gray in the ring. “I’m gonna be a lot better. It’ll be a lot closer. It’ll probably be in December, [at] the end of the year. I say we gotta do it again. Hopefully it’ll happen at 154.”

Spence still didn’t blame his lopsided loss on his grueling weight cut.

“He was just better tonight,” Spence said. “He was using the jab. My timing was a little bit off. He was just the better man tonight.”

Crawford seemingly took the eighth round off before he resumed his vicious assault on Spence as soon as the ninth round began. He finished off his decimated rival soon thereafter.

As a sign of respect, Crawford went out of his way to touch gloves with Spence after he dropped him twice during the seventh round.

A short right hook by Crawford knocked Spence clear off his feet with one second to go in the seventh round. That marked the second time Spence went down during the seventh round and the third knockdown of the fight for Crawford.

A counter right hook by Crawford sent Spence to the canvas for the second time in the fight with just under two minutes to go in the seventh round. Spence again got up quickly, but looked confused by what Crawford was able to do to him.

Crawford stung Spence with a right-left-left combination a little less than 20 seconds into the seventh round.

Spence held Crawford after absorbing another left hand late in the sixth round. Crawford countered Spence with another clean left with 1:15 to go in the sixth round.

Crawford caught Spence with a right hook to his body with slightly more than a minute remaining in the fifth round. Crawford continued to land hard jabs as Spence came forward with just over 1:40 to go in the fifth round.

A ringside physician examined Spence as Spence stood in his corner before he would allow the fifth round to begin.

Crawford staggered Spence with a stiff jab that connected with just under 40 seconds remaining in the fourth round. Crawford drilled Spence with an overhand left that moved him backward with just over 1:45 to go in the fourth round.

By then, Spence bled from his nose.

Crawford previously landed two left hands with a little more than a minute remaining in the fourth round.

Crawford landed a hard jab with just under 35 seconds to go in the third round. Crawford connected with another jab that backed up Spence about 15 seconds later.

Spence, seemingly motivated by the knockdown he suffered late in the second round, attacked Crawford as soon as the third round began. Crawford fended him off, though, and the action returned to the center of the ring.

Crawford caught Spence with a counter right that sent Spence to the seat of his trunks with 20 seconds to go in the second round. A stunned Spence beat Dock’s count very quickly, but he appeared hurt until the bell sounded to end the round.

Crawford partially blocked Spence’s left hand about 15 seconds into the second round.

The first round was predictably uneventful until Crawford connected with a straight left hand, just after Spence missed with a left, when there were 30 seconds remaining in it.

Spence backed Crawford into the ropes just before the midway mark of the opening round, but Crawford tied him up. Crawford unsurprisingly started their fight in a southpaw stance.

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.