UFC debutants are often well aware that they will face higher-level competition than what they've grown accustomed to from their experience in lesser promotions. Thus, many mixed martial artists brace themselves for the stiffest challenges under the brightest lights in the sport.
However, most promotional debutants aren't immediately thrown to the wolves, forced to face top-level foes unless they're former world champions from the likes of Bellator. Michael Chandler was such a case. However, in the rare occasion, fighters make their debut against former or current champions.
This isn't to say that they debuted against someone who goes on to win a title and is either currently holding it or once did. These are foes who were either reigning champions or former titleholders when they welcomed UFC fighters. One, in fact, is competing at UFC 300.
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#5. Yana Santos, UFC women's bantamweight/former featherweight
The women's featherweight division is extinct, and now, Yana Santos, married to former light heavyweight title challenger Thiago Santos, fights in the 135-pound weight class. However, when the women's featherweight division still existed, Santos debuted in the weigt class.
Check out Yana Santos losing to Cris Cyborg:
Only, she didn't debut against just any fighter. She debuted in a title fight against the then reigning 145-pound champion and WMMA great, Cris Cyborg. To no one's surprise, Santos was overmatched and had little to no chance of dethroning the legendary Brazilian, getting TKO'd within three minutes of round one.
She hasn't come close to title contention since, and is currently on a three-fight losing streak, having not fought since July 1, 2023.
#4. Ben Askren, former UFC welterweight
For years, Ben Askren had been the subject of tremendous hype. He was a welterweight titleholder in both Bellator and ONE Championship, undefeated, and one of the highest-level wrestlers in MMA. Thus, many were interested in watching him compete in the UFC. Finally, in 2019, fans got their wish.
'Funky' was matched up with former welterweight champion Robbie Lawler for his debut fight. The bout, however, also seemed like a fraud check, as Askren was slammed on his head and battered into a bloody mess by follow-up ground-and-pound before the pair worked their way back to their feet.
Check out Ben Askren's controversial win over Robbie Lawler:
Askren scored a takedown, teasing a rear-naked choke. When Lawler tried to spin out of it, Askren transitioned into a bulldog choke, which caused referee Herb Dean to call the fight when it seemed like 'Ruthless' fell unconscious, which Lawler contested. The result is controversial and is Askren's only win in the promotion.
#3. Liz Carmouche, former UFC women's bantamweight/flyweight
After a two-fight win streak in Invicta FC, Liz Carmouche was signed by the UFC to take on Ronda Rousey, who had been recently promoted from the Strikeforce women's bantamweight champion to the UFC's. She was to be Rousey's first title defense, and Carmouche was up to the task.
Alas, she was in over her head, and quickly fell victim to Rousey's signature armbar within four minutes of round one. It was a nearly insurmountable challenge, especially given the vast skill difference between the two. However, she would not come close to a title shot for six years.
Check out Liz Carmouche's loss to Ronda Rousey:
Eventually, moving back down to women's flyweight, she faced Valentina Shevchenko in a rematch. Only this time, it was for the 125-pound title. Unfortunately, she lost via unanimous decision.
#2. Joe Soto, former UFC bantamweight
After T.J. Dillashaw scored a massive upset by dethroning Renan Barão for the bantamweight title, the pair were scheduled for a rematch at UFC 177. At this time, Joe Soto was set to make his promotional debut against Anthony Birchak. That plan though was derailed at the weigh-ins.
Barão had a disastrous weight cut that landed him in the hospital. With no other choice, the promotion reshuffled the matchups, scrapping the Birchak fight and offering Soto the chance to face Dillashaw for bantamweight gold, even if only on incredibly short notice.
Check out Joe Soto losing to T.J. Dillashaw:
Soto accepted the bout and faced Dillashaw, the then-reigning bantamweight champion, on his debut. As expected, he lost, getting TKO'd in round five. He never fought for a world title thereafter.
#1. Kayla Harrison, UFC women's bantamweight
Kayla Harrison is a potential star in women's MMA. She spent the majority of her career in the PFL as its women's lightweight champion. Now, the two-time Olympic judo champion will make her promotional debut this Saturday, where she faces former women's bantamweight champion Holly Holm.
Not only will it be Harrison's first bout in the promotion, against a former champion, but it will also be her first fight at 135 pounds. There have been concerns about her ability to make weight, as Holm has implied that a Harrison weight-related failure would be intolerable and she would not accept a catchweight bout.
But as things stand, Harrison will take on Holm, and a win may very well launch her into title contention.