Ryan Garcia says he had never been knocked down before when an early blow sent the rising star to the canvas in his biggest test yet against Luke Campbell.

The 22-year-old Californian had an impressive response, staggering Campbell with a body blow to win a WBC lightweight title fight on a seventh-round knockout Saturday night.

Garcia was in control when his left hand crushed Campbell's right side and sent the English fighter to one knee at 1:58 of the seventh. Campbell couldn't get up, giving the undefeated Garcia his 18th knockout in 21 fights.

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"That was the hardest shot I was ever hit with," Campbell said. "I tried and tried to get up, but I couldn’t. I felt him coming on, and I was moving back, and when you move back, my body relaxed a little bit and that’s the exact time he hit me."

Campbell (20-4) knocked down Garcia with a left hook in the second round, but didn't land many other punches while Garcia was the more aggressive fighter until the decisive blow.

The bout was postponed about a month because Campbell tested positive for COVID-19. It was moved to Texas because of coronavirus restrictions in Garcia's home state.

"I've never been dropped in my life," said Garcia, who is matching his large social media following with a flair for the dramatic inside the ring. "I think I got a little too excited in the moment."

Campbell had lost two previous title fights after winning a gold medal at his home Olympics in London in 2012.

It was the fifth straight knockout for Garcia since what his camp considered a disappointing majority decision over Carlos Morales in 2018.

"This is the kind of fight where superstars are made," promoter Oscar De La Hoya said. "Down on the mat early for the first time in his career, Ryan got up, rallied, broke down his man and got the knockout."

Garcia easily won the first round before Campbell's left hook midway through the second. Garcia regained control by continuing to attack and by the fourth round asserted himself with a right-left combination and a quick answer to a strong right from the lefty Campbell.

"I was a little dizzy with the knockdown, but I wasn’t worried," Garcia said. "He’s not used to going forward, so I just knew I had to cover up."

Late in the fifth round, Garcia sent Campbell staggering to the ropes just and confronted the 33-year-old after the bell had rung. Garcia tried to pick up where he left off at the start of the sixth, but backed off after an aggressive start to the round.

Garcia did most of the attacking, while Campbell seemed content to counterpunch.

"He never fights coming forward, so I knew he would back up throughout the fight," Garcia said. "I’m naturally a counterpuncher. But today I showed that I can be aggressive, go forward and take it to somebody."

All three judges had Garcia comfortably ahead when Campbell went down, with two of them giving the Los Angeles-area fighter four consecutive rounds before the seventh.

Asked about his next fight, Garcia said he wanted to face Gervonta Davis but also mentioned Devin Haney.

"I didn’t let anything stop me from being a champion tonight," Garcia said. "Even when he dropped me, I knew that couldn’t stop me from being champion."