LOS ANGELES (AP) — Marcos Maidana stopped Victor Ortiz early in the sixth round of an action-packed fight Saturday night, using a punishing right hand to upset one of boxing’s top prospects.

Maidana (26-1, 25 KOs), a 140-pound Argentine who fights mostly in Germany, was knocked down three times in the opening two rounds of his first fight in this country. Yet Maidana also flattened Ortiz in the first round, and he steadily landed punches until Ortiz finally was forced to stop, his face badly cut and terribly swollen.
“I went down, but I got up because I have a big heart,” Maidana said. “I saw that Victor felt my punches, and I said, ’I know I can win this.”’
Ortiz (24-2-1) was the most promising youngster in Golden Boy Promotions’ stable of up-and-coming fighters, but the Kansas native couldn’t maintain his aggressive early pace and took far too many big shots. After he was rendered unsteady and bloody from the final knockdown, the ringside doctor stopped the fight.
Ortiz had knocked out his last eight opponents, but the talkative fighter was left practically speechless by Maidana’s power and resilience. He finished with a large cut near his right eye and a badly damaged left eye.
“I don’t know what happened,” he said. “I wasn’t in the zone tonight. He packs some power behind those punches. I usually keep composed, and tonight I wasn’t. ... I made some mistakes. I wanted to take my time and finish him, but I was hurt.”
Ortiz connected on 42 percent of his 177 punches. Maidana was much busier with 293 punches, connecting with 23 percent.
Maidana incurred his only loss in February on a split decision against Andreas Kotelnik. Maidana felt robbed by sketchy judging that favored Kotelnik, who lives in Germany — and he left nothing to the scorecards against Ortiz.
Ortiz couldn’t live up to the expectations of an enthusiastic crowd supporting him in his first main-event bout at Staples Center, near his adopted Southern California home. Ortiz had never headlined a card in such a large venue, but Oscar De La Hoya was eager to turn him into a star.
Both fighters moved forward furiously from the opening bell, and Ortiz knocked down Maidana for the first time on a big right hand with about 1:15 left. With the crowd standing and cheering for Ortiz, Maidana improbably landed a straight right hand that put Ortiz flat on his back.
The crowd was stunned, but Ortiz popped back up, and both fighters made it to the bell. The second round was just as competitive, with the boxers trading shots until Ortiz knocked down Maidana with a right hook with about 30 seconds left — and then did it again with a shorter version of the same punch right before the bell.
But Maidana landed several big shots in the next three rounds, rocking Ortiz with two powerful right hands in the final seconds of the fifth. Ortiz also developed that big cut, which gaped open when the fight ended 46 seconds into the sixth.
“I came to look to finish him, and that’s what happened,” Maidana said. “He hits very hard, but he doesn’t have a good chin. Definitely he didn’t adjust to my rhythm.”
Chris John, the Indonesian featherweight champion who backed out of his co-main event rematch with Rocky Juarez this week because of an illness, appeared in the ring before the final bout. He waved to several hundred flag-waving Indonesian fans who bought tickets thinking they would see John’s second fight in this country.
The undercard fighters entered the ring to the strains of remixed Michael Jackson songs, and Ortiz made his ring walk to a “Beat It” and “Thriller” mash-up. A ceremonial 10-count was rung in honor of the pop star who died Thursday in Holmby Hills, about 12 miles from Staples Center. Jackson spent many nights rehearsing at the arena during the past two months for his 50 scheduled summer appearances in London.