Kamaru Usman and Gilbert Burns have faced off hundreds of times with each other in practice. On Saturday, they'll do it for real.

Usman will defend his UFC welterweight title against Burns, his former sparring partner, in the main event of UFC 258 in Las Vegas.

Purchase UFC 258 here.

"I know a lot about Kamaru," Burns told ESPN. "I know exactly how he wants to fight. I know a lot about him. On the other hand, he knows a lot about me, too. It's just different. I don't care. It is what it is. We're gonna go out there, I'm gonna try to knock him out or submit him."

Usman and Burns had been training together in South Florida since 2012, first with the Blackzilians, then HKickboxing and finally with Sanford MMA. Usman departed for Colorado to train under coach Trevor Wittman last year after the initial fight with Burns was scheduled for July. But Burns tested positive for COVID-19 and withdrew from that bout.

While Wittman will corner Usman, Burns will be missing longtime coach Henri Hooft, who has decided to sit this one out because he also coached Usman before he switched gyms.

Usman, a Nigeria, native is 12-0 in the UFC -- one win short of Georges St-Pierre's record 13 straight UFC welterweight wins. Usman, 33, is coming off a unanimous-decision win over Jorge Masvidal at UFC 251 last July.

Burns (19-3) has won six in a row, the most recent a unanimous decision win over Woodley last May. The Brazil native is 4-0 since moving up to welterweight from lightweight in 2019. Burns, 34, is a multiple-time Brazilian jiu-jitsu world champion with power in his hands. He's trying to become the first Brazilian to win the UFC welterweight title.

In the co-main event, Maycee Barber and Alexa Grasso will meet in a battle of promising women's flyweight up-and-comers. The 22-year-old Barber (8-1) is trying to bounce back from her first career loss, as well as ACL surgery. Grasso (12-3), a 27-year-old Mexican striker, is looking to put together her first UFC winning streak.

Also on the undercard, former top middleweight contender Kelvin Gastelum tries to snap a losing streak against Ian Heinisch and dominant Brazilian jiu-jitsu star Rodolfo Vieira tries to stay undefeated in MMA against Anthony Hernandez.

Fight in progress:

Middleweight: Maki Pitolo (13-7, 1-3 UFC, +145) vs. Julian Marquez (7-2, 1-1 UFC, -170)

Results:

Middleweight: Anthony Hernandez (8-2 1 NC, 2-2 1 NC UFC) defeats Rodolfo Vieira (7-1, 2-1 UFC) by second-round submission

Vieira came in as a heavy favorite, the odds-on pick to dominate with his oppressive ground game. Vieira is a five-time Brazilian jiu-jitsu world champion, a former prestigious Abu Dhabi Combat Club gold medalist and a monstrous MMA prospect.

Then, Hernandez did the impossible.

After Vieira started to tire in the first round, Hernandez took over. He beat up Vieira on the feet, cut him with elbows and then -- incredibly -- submitted Vieira with a guillotine choke. The finish came at 1:52 of the second round. Hernandez winning by submission was +1600, per Caesars Sportsbook by William Hill, and just emerging victorious was +370.

Submission of the year. Congrats @Ilovebamf. That was amazing! #UFC258

— Michael Chiesa (@MikeMav22) February 14, 2021

"I knew I was gonna do it," Hernandez said in his postfight interview ... "I've never felt more ready for a fight."

Vieira came out right away in the first round and picked Hernandez up for a big slam. He quickly got into mount and worked for an arm triangle. Hernandez survived and made his way back to his feet. When he did, Vieira was gassed out and Hernandez started landing hard punches.

"I was like, Oh he's not that strong," Hernandez said. "My coaches just told me to be calm. ... I just stayed calm, listened to the game plan and made it happen."

Vieira took Hernandez down in the second round, but Hernandez escaped before Vieira could get to his back. On the feet, Hernandez cut Vieira with two elbows and then grabbed his neck in a scramble. Vieira had no choice but to tap in a shocking result.

Hernandez, 27, has won two of his last three fights. The California native has six submissions in eight pro victories, but said afterward he is just a purple belt in Brazilian jiu-jitsu. Vieira, a 31-year-old Brazil native, got hit with his first pro loss. He had finished every previous MMA bout.

-- Marc Raimondi

Watch this fight on ESPN+.

Welterweight: Belal Muhammad (18-3, 9-3 UFC) defeats Dhiego Lima (17-8, 4-6 UFC) by unanimous decision

Muhammad came out of his corner at the start of the fight and immediately began stalking his prey, and he didn't take one step backward during the three rounds that followed. His steady stream of punches never wobbled Lima but did wear him down, enabling Muhammad to earn his fourth straight victory.

Muhammad's domination made it easy for the judges, who all scored the bout 30-27.

Amazing performance by @bullyb170 amazing pace and boxing! #calfkicks suck don't they bully!?

— Paul Felder (@felderpaul) February 14, 2021

The 32-year-old from Chicago did not escape unscathed, however, as Lima landed an abundance of calf kicks throughout the three rounds, forcing Muhammad to switch stances and robbing him of some of the power in his punches.

But that was about all Lima was able to muster offensively. The leg kicks aside, the 31-year-old from Atlanta simply did not throw enough strikes. He occasionally countered a Muhammad attack, but mostly was outworked in the fisticuffs. It was his first fight in nearly a year and a half, and he looked rusty in seeing his three-fight win streak come to an end.

-- Jeff Wagenheim

Watch this fight on ESPN+.

Strawweight: Polyana Viana (12-4, 3-3 UFC) defeats Mallory Martin (7-4, 1-2 UFC) by first-round submission

If Viana keeps fighting like this, that 0-3 skid early in her UFC career will be a distant memory.

Viana picked up her second consecutive submission victory by tapping Martin with an armbar at 3:18 of the first round. It was another impressive showing for the Brazilian strawweight, who also tapped Emily Whitmire in the first round with an armbar in her previous performance in August.

Wow! Beautiful control and transitions by Viana! #UFCVegas18

— Alan Jouban (@AlanJouban) February 14, 2021

Martin, of Denver, was comfortable taking the fight to the ground and working out of Viana's guard, which proved to be a costly mistake. Viana caught her in a triangle from the bottom and then alternated back and forth between the triangle and armbar until the finish. She also landed a series of hard elbows to the top of Matin's head, while working on the submission.

Viana, who began her UFC career 1-3, is now 3-3 in the Octagon. Martin falls to 1-2.

-- Brett Okamoto

Watch this fight on ESPN+.

Catchweight (140 pounds): Chris Gutierrez (16-3-2, 4-1-1 UFC) defeats Andre Ewell (17-7, 4-3 UFC) by unanimous decision

Gutierrez got a kick out of a short-notice fight. Actually, several of them.

Using a superlative kicking game, Gutierrez outpointed Ewell via unanimous decision (30-26, 29-28, 29-27) in a 140-pound catchweight bout. The fight was put together earlier this week after Ewell's positive COVID-19 test forced him out of last weekend's UFC Fight Night card.

Chris Gutierrez has crazy timing with those calf kicks. That jump kick off the octagon was wicked! #UFC258

— Aljamain Sterling (@funkmasterMMA) February 14, 2021

Gutierrez damaged both of Ewell's legs with kicks. But those weren't the only targets of Gutierrez's dangerous legs. He dropped Ewell with a left head kick at the end of the first round. Ewell rebounded with a solid second round, taking Gutierrez down after catching a kick and working a heel hook.

In the third round, Gutierrez really opened up. With Ewell feeling the effects of leg kicks, Gutierrez landed a beautiful left kick counter with Ewell against the cage. Later, Gutierrez propelled his left leg off the cage and landed a kick with that same leg to Ewell's face. Gutierrez finished the bout looking for a mounted triangle on a grounded Ewell.

Gutierrez, 29, is unbeaten in five straight fights and looks like someone to watch in the bantamweight division. The Boston native has not lost since his UFC debut in 2018. Ewell, a 33-year-old California native, had a two-fight winning streak snapped.

-- Marc Raimondi

Watch this fight on ESPN+.

Welterweight: Gabe Green (10-3, 1-1 UFC) defeats Phil Rowe (7-3, 0-1 UFC) by unanimous decision

Green landed some big punches along the way, but it was his lower leg kicks that got the knockdowns, did the damage and secured his first UFC victory.

When the fight was being contested at distance, the taller Rowe used his reach to pick apart Green. And when the fight went to the canvas, Rowe also showed off a jiu-jitsu edge that put him in dominant positions on the canvas, close to setting up a submission. But Green dropped him twice in the second round and one more time at the start of Round 3, all with calf kicks. That was what swayed the judges in a close fight.

Gabe Green: "I've been waiting a very long time to see you."
Joe Rogan: "I've been waiting a long time to see you too. You walked the wrong way."@joerogan had a laugh with @giftedgabegreen ? #UFC258 pic.twitter.com/bOEV4kqVFl

— ESPN MMA (@espnmma) February 14, 2021

For Green, a 27-year-old from Downey, California, the victory got him back on track. He lost his UFC debut last May, ending a six-fight win streak.

On this night it was Rowe whose streak ended. The 30-year-old from Palm Coast, Florida, who was making his UFC debut, came in riding a seven-fight winning streak that dated back to his third pro fight.

Two judges scored the fight 29-28 for Green, and the third had it 30-27.

-- Jeff Wagenheim

Watch this on ESPN+.

Still to come:

Welterweight: Kamaru Usman (c) (17-1, 12-0 UFC, -270) vs. Gilbert Burns (19-3, 12-3 UFC, +220)
Women's flyweight: Maycee Barber (8-1, 3-1 UFC, +105) vs. Alexa Grasso (12-3, 4-3 UFC, -125)
Middleweight: Kelvin Gastelum (16-6 1 NC, 10-6 1 NC UFC, -220) vs. Ian Heinisch (14-3, 3-2 UFC, +180)
Men's featherweight: Ricky Simon (17-3, 5-2 UFC, -240) vs. Brian Kelleher (22-11, 6-4 UFC, +200)
(c) = defending champion