Harrison, Pacheco, Cooper and Michaud secure spots in PFL finals

One of the PFL's biggest hooks, besides the $1 million first-place payday, was the fact that five of six divisions required fighters to win twice in one night of playoff action to clinch a spot in the finals.

That requirement and the quirks of the PFL's playoff format and rule set loomed large on Friday at the Mandalay Bay Events Center in Las Vegas. Top-seeded Magomed Magomedkerimov was forced to drop out of the welterweight bracket after defeating Chris Curtis in the quarterfinals, meaning Curtis would step into his place in the semifinals. The only problem? Curtis retired between fights and had to scramble to get ready to fight Ray Cooper III.

Cooper won by KO and advanced to his second straight PFL final.

Curtis wasn't the only fighter to retire on the night. After losing in the semifinals to David Michaud, top seed Glaico Franca retired and proposed to his girlfriend through the TV screen, all at once. Ultimately, it'll be Cooper vs. Michaud, who came back from a 17-second knockout loss to Sadibou Sy to open the season and won three straight to qualify for the finals.

At women's lightweight, Kayla Harrison took care of business with a scientific submission win over alternate Bobbi Jo Dalziel. On the other side of the bracket, top seed Sarah Kaufman was defeated by Brazil's Larissa Pacheco in her semifinal fight, short-circuiting the anticipated star-studded final. Instead, there will be a rematch of the regular-season fight in which Harrison defeated Pacheco but cried afterward because she couldn't finish the fight.

Let's break down a wild night in Las Vegas.

This file was updated in real time.

Welterweight semifinal: No. 5 David Michaud def. No. 1 Glaico Franca by majority decision

It was a tough night for the No. 1 seed at welterweight. Franca took a beating earlier in the evening in a victory over Andre Fiahlo but made it to the semifinals -- and the damage continued at the hands of Michaud. Franca got in his licks, especially in the grappling early, but as time wore on, he couldn't stand up to the relentlessness of Michaud, who stalked him for three rounds and hurt him with punches and knees on several occasions.

Despite a one-two combo of a seemingly unintentional low-blow knee followed by a knee to the head that opened a cut on Michaud's head, the damage only seemed to energize the eventual winner.

Two of the judges scored the fight 29-28 for Michaud, and the other saw it as a draw. Afterward, Franca announced his retirement, then made a bid for at least one victory on the evening: He preempted Michaud's postfight interview for a moment as he publicly proposed to his girlfriend.

As for Michaud, he moves on to the New Year's Eve final against Ray Cooper III.

Welterweight semifinal: No. 6 Ray Cooper III def. No. 7 Chris Curtis by second-round KO

Some fighters might have been thrown off, but not Ray Cooper III.

Cooper knew a win earlier in the night would bring him back to the cage. He also knew that if the bracket fell right, he would be stepping in for the rematch with Magomed Magomedkerimov that he had craved since Magomedkerimov defeated him in last year's $1 million PFL welterweight final.

The bracket went the way Cooper had been hoping ... until it didn't. He won his first fight of the night, and so did Magomedkerimov, setting up the rematch. But then Magomedkerimov was unable to come back and fight, and he was pulled from the semifinal. He was replaced by Chris Curtis, whom he'd beaten earlier in the evening. Curtis, for his part, had left his gloves in the center of the cage as a sign that he was retiring and then confirmed it with a post on Instagram.

Cooper (19-7) took it all in stride, and Curtis (21-7), to his credit, came to fight. In fact, he showed more life in his second bout than he had against Magomedkerimov. But Cooper is a dangerous man, and when Cooper's right hand caught up with Curtis' chin, it did so in a big way. The monstrous punch, just 11 seconds into Round 2, sent Curtis back into retirement, bouncing his head off the mat and flattening him along the way.

Women's lightweight semifinal: No. 2 Kayla Harrison def. No. 5 Bobbi Jo Dalziel by first-round submission (armbar)

Harrison showed everyone on Friday's card a thing or two with the most decisive finish of the night. Even though she needed to fight only once to gain a spot in the New Year's Eve women's lightweight final, Harrison showed what was lacking for most of the night among the two-fights-in-one-night welterweight men. She sustained zero damage after seizing advantage in the opening seconds, getting an immediate takedown and never allowing Dalziel to get back into the fight.

Dalziel (5-2), a late replacement for Genah Fabian, managed to climb to her feet briefly, only to once again get taken to the canvas. From there, Harrison (6-0) used her Olympic judo to quickly yet patiently work for an armbar. The tap out came at 3:32 of Round 1 and sent the second-seeded Harrison to a rematch with Larissa Pacheco, whom she defeated by unanimous decision in May.

Women's lightweight semifinal: No. 1 Sarah Kaufman vs. No. 4 Larissa Pacheco

The first semifinal of the night provided the first significant upset of the PFL playoffs, as Pacheco proved to be too much for the top-seeded Kaufman.

Pacheco, who cut weight to make the 155-pound lightweight limit, was bigger and stronger than Kaufman, who fought at 135 pounds for all of her 13-year career before opting into this $1 million chase in the PFL. It wasn't simply size that got the job done for fourth-seeded Pacheco (12-3), though. She was the better striker from distance, and that showed on Kaufman's face, which by Round 2 was as red as her PFL fighter kit.

Kaufman (21-5) kept coming forward and landed the occasional solid punch, but Pacheco slipped a lot of Kaufman's offense with footwork and head movement, and she always had a counter-strike. When Pacheco took the fight to the canvas, she kept it there. The judges scored the fight 30-27, 30-27 and 30-28, all for the 25-year-old Brazilian, who advances to the Dec. 31 finale.

Welterweight quarterfinal: No. 5 David Michaud def. No. 4 John Howard by unanimous decision

This fight got going with an early exchange of punches, which ended with Howard landing a solid right hook that sent Michaud moving backward. It was clear at that point that he didn't want any of the "Doomsday" power, so the next time Michaud advanced, he did so in pursuit of a takedown. He got it, and that put Michaud in control for the rest of Round 1.

But Howard (28-16-1), the No. 4 seed, had an answer for the wrestling in the second. He scored a couple of takedowns of his own -- one on a big slam -- and fended off Michaud's clinch offense. Howard also landed several good punches and had fifth-seeded Michaud (17-5) on his heels, looking to clinch again. When it ended, it looked like a Howard round, evening the score. But all of the judges scored both rounds for Michaud (20-18, 20-18, 20-18), who moved on to the semifinal against No. 1 seed Glaico Franca.

Welterweight quarterfinal: No. 2 Magomed Magomedkerimov def. No. 7 Chris Curtis by unanimous decision

Magomedkerimov deployed a strategy befitting a returning champion by winning his first fight of the night while absorbing little damage. He did this by keeping his focus on another "D": distance. The No. 2 seed kept the fight where he needed it to be to succeed against the boxing-heavy Curtis (21-7). At times he kept it on the outside, where his footwork and jabs kept him safe, and at other points in the fight, Magomedkerimov closed distance to smother his opponent's weapons.

This was a rematch of a fight in July, also won by Magomedkerimov, who took a decision the first time around, despite breaking his hand early. He is healthy now, and he kept it that way in his opening fight of the night, winning both rounds on all scorecards, with one judge penciling in a 20-17 score. The win would have set up a semifinal bout against Cooper, whom he defeated in last season's PFL final to secure the $1 million first-place prize.

Later in the night, Magomedkerimov was unable to continue, so Curtis took his place in the semifinal round against Cooper.

Welterweight quarterfinal: No. 1 Glaico Franca def. No. 8 Andre Fialho by majority decision

Franca, the No. 1 seed, had some perilous moments at the start of Round 2, wobbled by a punch that sent him into survival-mode retreat. Fialho, seeded eighth, followed in pursuit and landed several crisp punches, a few of which snapped back Franca's head, but ultimately, there was no finishing blow in the attack.

After 30 seconds of trouble, Franca turned things around by rushing in for a takedown, which provided him the respite he needed to clear his head and a controlling position to help earn him back the round.

At least, that's the way two judges saw it, as a pair of scorecards gave Franca (22-5) a 20-18 sweep over Fialho (10-3). The other judge scored the bout a 19-19 draw. That was enough for the top seed to move on to the semifinals.

Welterweight quarterfinal: No. 6 Ray Cooper III def. No. 3 Sadibou Sy by judges' decision (majority draw, all three judges picked Cooper)

And so the playoffs began ... and boy, did they ever get off to a high-energy start. Cooper and Sy got after it right from the start, until Sy landed a kick midway through the first round that slowed Cooper (18-7-1) for a beat. Then the Hawai'ian resumed his surge forward, as he is wont to do. He dropped Sy (8-5-2), let loose a flurry trying to finish and then settled for taking control on the mat.

Before the round was over, Sy managed to get back to his feet, and he proceeded to drop Cooper and swarm him with punches before the bell. It was a tough round to score, but one thing was not in dispute: Both guys took more damage than one would want to absorb on a night when you hope to be fighting again.

Round 2 brought more damage to Cooper, as Sy landed several sapping knees to the body. One got Cooper in the groin and brought a pause in the action that served both tired fighters. But from that point on, neither man made the clearest case to distinguish himself from the other.

That was reflected in the judges' scorecards, as the judges called the bout a majority draw (though no scores were announced). Ultimately, they sent Cooper -- bloodied face and all -- to the semifinals.