'I was worried about bleeding on McGregor's expensive shirt'

I have fought 21 times as a professional boxer. I am a former world champion who has faced Claressa Shields and Savannah Marshall and been on some massive stages.

Yet there was a strong feeling of the unknown when I made the ring walk for my bare knuckle debut in a bullfighting arena in Marbella which looked like a mini colosseum.

I felt electric, like a gladiator. This was a completely different sport to boxing.

You cannot spar without gloves when training for bare knuckle, so I had no real idea how it would actually feel to punch – and be punched – without protection on your fist.

Immediately before the start, the referee told us to "tow the line" – which is different from boxing as there are no opposite corners in the circular BKFC ring.

You are told to "knuckle up" as you stand beside your opponent. There is no feeling out process before meeting in the centre of the ring.

During the first two rounds I was learning on the job, but halfway through the third I found my range and flow. I put my combinations together and I then understood what this sport was all about.

After my win, loads of boxers - including Sandy Ryan and Chantelle Cameron - messaged to congratulate me.

My good friend Shields sent a voice note saying: "Bestie, you're officially the crazier one out of the two of us."

I needed a new challenge and bare knuckle fighting has always fascinated me. Yes, you are throwing punches, but your opponent will come at you a lot faster than boxing.

The stance is different and you can even hold and hit, so I had to get used to the grappling part.

When you throw a punch, you have to make sure you are making a tight fist so as not to hurt your hand when you land.

Accuracy is so important too. You do not want to land knuckle on elbow - bone on bone - although inevitably that is what happens.

Financially, it is much better for me than boxing. Just like the UFC, there are opportunities to increase your purse with fight-of-the-night and knockout bonuses.

A lot of it is down to former UFC champion Conor McGregor, who is a part owner of BKFC. His involvement has really blown the sport up.

People judge him on being loud, lairy and full on but McGregor is so obsessed about all combat sports and his energy is infectious. It is not just for the cameras. He is working non-stop, 24/7, promoting BKFC.

He was messaging me throughout my camp to see how my training was going, and he gave me a big hug after the fight, telling me I was a warrior. I was worried my cut was going to bleed on his very expensive shirt.

My dad has attended all my boxing matches apart from two during the pandemic. I will always be my daddy's little girl. But I said this time he had no obligation to be there.

"Yeah, I think I might give this one a miss, Hannah," he told me. As soon as I finished the fight, my head coach phoned my sisters and dad to let them know everything was fine.

Everyone says bare knuckle must be very dangerous and there is no protection, but I can honestly say that the pre-fight and after-fight medical care for my fight on Saturday was better than any boxing situation I have been in.

What people sometimes don't realise - and some of my family didn't - is that it is only five two-minute rounds. I'm not in there for a 10-round war like I would for a world title boxing fight.

A lot of the injuries are superficial – they are cuts and not the same as taking repeated blows to the head with gloves which could end up in something serious.

I plan to be back out again in the US in the new year. I would never rule out a return to boxing, buy my goal now is to win a bare knuckle world title and become a two-sport world champion.

Hannah Rankin was talking to BBC Sport's Kal Sajad.