Jeremy Stephens KO's Doo Ho Choi in UFC Fight Night headliner

Jeremy Stephens has been in the UFC for more than 10 years, and his punching power is no secret by now. But it still carries a shock factor.

Stephens (27-14) delivered a jaw-dropping knockout against Doo Ho Choi on Sunday, finishing the Korean prospect with a pair of monstrous right hands in the second round. The featherweight bout headlined UFC Fight Night at Scottrade Center in St. Louis.

The upset finish came at the 2:36 mark. Stephens dropped Choi with an overhand right behind the ear and stood over his guard. As Choi tried to cover up, Stephens dropped down with another vicious right hand that ended the fight.

It marked the 18th knockout victory of Stephens' career. The 31-year-old leapt over the Octagon immediately after to embrace members of the crowd.

"Brian Ortega, I know he's coming off a good win," said Stephens, when asked whom he wanted next. "Right now I want to celebrate."

Choi (14-3) was on point in the opening round and more or less in control of the action. He used his height and reach advantages effectively, keeping Stephens on the end of frequent kicks and stepping out of range whenever Stephens pressed forward.

The tone of the matchup changed dramatically in the second round, however, as Stephens found success with leg kicks of his own. He also landed several thudding kicks to the body and snapped Choi's head back with the jab.

Stephens, who fights out of San Diego, has been inconsistent in recent years, with a 4-5 record in his past nine contests. He has now won two in a row, however, including a decision over two-time UFC title challenger and Strikeforce champion Gilbert Melendez.

Choi, 26, drops to 0-2 in his past two appearances. He suffered a close loss to Cub Swanson in December 2016 before missing all of 2017 to injury.

Clark climbs ladder, takes out VanZant

Flyweight Jessica-Rose Clark (9-4) picked up a decision victory over Paige VanZant (7-4), which improved her UFC record to 2-0.

All three judges scored it for Clark: 30-27, 29-28 and 29-28. She nearly submitted VanZant with a triangle choke in the second round. VanZant, 23, appeared to suffer a right arm injury early in the fight, and tweeted afterward that the arm was broken.

It was a difficult week for Clark, as she found out her Las Vegas home was robbed shortly after she left town. An investigation is underway.

"They stole $30,000 worth of stuff and killed my cat," Clark said. "This week was tough. The weight cut, getting that out of my head. But we came in and did what we needed to do."

Originally from Australia, Clark took a blue-collar approach against VanZant, who was coming off a 13-month layoff. She walked VanZant down with boxing combinations and won the key grappling exchanges. VanZant connected on several hard kicks and knees but Clark never appeared hurt.

It has been tough sledding for VanZant in recent years. After a 3-0 start in the UFC, she has lost three of her past four.

Usman stays perfect in UFC, calls out Covington

Nigerian welterweight contender Kamaru Usman (12-1) is in line for a big fight after dominating Emil Meek (9-3-1) in a lopsided three-round decision. All three judges scored it 30-27 for Usman.

The former collegiate wrestler easily took Meek down and controlled him on the floor, pushing his win streak to 11 in the process. After the bout, he called out Colby Covington, who has won his past five.

"I fought this fight, sitting at 30 percent," Usman revealed. "That was 30 percent, and I dominated a so-called 'Viking.' I'm the most dominant and well-rounded welterweight on the planet. Nobody can stop me. That's why they're all afraid to fight me."

Meek, of Norway, had one glimmer of hope in the second round, when he surprised Usman with a spinning backfist after defending a takedown attempt. Usman appeared to be dazed momentarily from the shot but recovered quickly.

Unheralded Elkins submits Johnson, extends streak

Featherweight Darren Elkins (24-5) ran his win streak up to six as he submitted Michael Johnson via rear-naked choke at 2:22 of the second round.

Most of the prefight talk was on Johnson (17-13), a former lightweight who is originally from St. Louis. The 31-year-old looked good early, connecting on several good left hands and shutting down Elkins' attempts at a takedown.

But Elkins, who trains out of Sacramento, secured a takedown in the opening minute of the second round and quickly took Johnson's back in a scramble. He has made a habit recently of giving away early rounds before storming back to comeback wins.

"I want a No. 1 contender, and I think that's realistic," Elkins said. "I've got six [in a row]. The only one with a longer win streak than me is [champion Max Holloway]."

Johnson has now been finished in his past three fights and has dropped five of six.