UFC has a main event for its New York return.

Al Iaquinta, a winner of five straight bouts, will step in and fight in the main event of UFC 223 on Saturday after two other challengers were forced to drop out.

Iaquinta has agreed to fight Khabib Nurmagomedov in a lightweight bout at Barclays Center, steadying a promotion thrown into upheaval following criminal charges against star Conor McGregor.

Max Holloway had agreed to fight Nurmagomedov on Saturday on just six days’ notice after original challenger Tony Ferguson injured a knee. But Holloway was unable to reach the weight limit for the bout today and was ruled out by the UFC medical team.

Holloway apologized on Twitter to Nurmagomedov, saying he wants “to keep going but they are stopping me. Sorry to your team and the fans.”

UFC then scrambled to find a last-second sub for Holloway in the headline bout at a sold-out Barclays in Brooklyn.

Iaquinta, who was scheduled to fight Paul Felder, got the nod.

Iaquinta did not meet the 155-pound limit — he came in at 155.2 — when he weighed in this morning for his fight against Felder before Holloway was scratched. Nurmagomedov, a native Russian, will become the lightweight champ should he win. Iaquinta will not be crowned the champ with a victory. UFC President Dana White said tonight he could decide to make Iaquinta the champ with a victory.

“If he wins, we’ll figure it out,” White said.

UFC offered full refunds because of the changes to the main event.

Holloway already was the 145-pound champion and was trying to become a two-division champ by beating the undefeated Nurmagomedov in the 155-pound title fight. Holloway and Nurmagomedov were fighting for the lightweight title left vacant by McGregor’s nearly 18-month absence.

The original card had shaped up as the best of the year and White said it was trending toward the best pay-per-view buy rate since McGregor’s last fight at UFC 205.

But the backstage melee McGregor allegedly instigated because of his anger toward Nurmagomedov instead has forced the removal of three fights because of injuries from the attack.

“To be honest, I hope he’s going to fix his problem,” Nurmagomedov said. “We have to fix our problems between me and him. Inside the cage or outside the cage, it doesn’t matter, we have to fix this.”

Artem Lobov, a close friend of McGregor’s, was pulled from the card for his involvement. Michael Chiesa and Ray Borg were hurt in the mayhem and forced off the card.

Video footage appears to show the promotion’s most bankable star throwing a hand truck at a bus full of fighters Thursday after a news conference at the arena. McGregor was released today on $50,000 bond.

McGregor stole the headlines while UFC matchmakers worked behind the scenes on a new main event. Former UFC lightweight champion Anthony Pettis was available after his fight against Chiesa fell through. Felder, an actor-turned-MMA fighter, was another lightweight on the main card who offered to fight Nurmagomedov but his request was denied.

Felder, who has won three straight fights and five of six, wrote on Twitter that the state athletic commission said he was not ranked high enough to earn the title shot.

“I tried to get it. Commission is stopping it,” he tweeted.

Felder and Pettis will receive bouts at a later date. White said all fighters bumped off the card will be paid.

Without a main event, UFC likely would have nudged the co-main event to headline status, and it’s a doozy: Rose Namajunas defends the 115-pound UFC strawweight championship against Joanna Jedrzejczyk in a rematch from their fight in November at Madison Square Garden.

Namajunas (17-3) used a devastating left that dropped Jedrzejczyk (14-1) in their first fight and the Colorado-based champ finished her with a series of lefts in a decisive first-round victory.

Namajunas is billed as “Thug” and brought gasps a few years back when she shaved her long, blonde locks in favor of a cropped cut that resembled Ripley in “Aliens.” She choked back tears at the Garden when White slapped the championship belt over her shoulder and fans drowned her out with cheers as she tried to put into words what the victory meant.

The victory not only ended Jedrzejczyk’s undefeated run, but she failed to tie Ronda Rousey for the UFC women’s record of six straight successful title defenses.

UFC has spent the past 18 months craving a new box-office star that can carry the promotion in 2018 and beyond while the reliable fan favorites are sidelined.

Jon Jones is facing a potential four-year ban because of a failed drug test. McGregor’s last fight was against a bus. Rousey quit to join WWE and makes her debut Sunday at WrestleMania. Former UFC heavyweight champion Brock Lesnar headlines ‘Mania. White has said the box-office titan who last fought at UFC 200 should return to the promotion this year.

Namajunas, who was on the bus McGregor attacked, had fans this week at a Brooklyn news conference going wild each time she took the mic. The soft-spoken Namajunas, who eschews trash talk for the power of positivity, said the upset win of 2017 was no fluke.

“I’ve got some new muscles,” she said. “I’ve got more knowledge. But my spirit’s the same. I’m like a tree. My leafs might change color, but my roots are the same.”