IF Savannah Marshall's MMA debut was anything to go by then her future appearances in the cage will be worth watching.

After four-and-a-half brilliant and breathless minutes, the brave resistance of her Brazilian opponent Mirela Vargas was broken. It was at that stage that an opponent from the past and the future stepped forward and, as is so often the case with Marshall, talk turned to Claressa Shields.

The long-time rivals are going to go at it again, that is certain. But what is not clear at this stage are the details. Will it be in the ring or the cage? The UK or the US? And the weight?

Marshall, Shields, Dan Hardy, head of fighter operations for PFL Europe, and Ben Shalom, Savannah's boxing promoter, all had their say in a manic hour that followed the fight.

Manic doesn't do justice to the fight itself. It was, in Marshall's words: "Mad, absolutely crazy."

And it didn't pass without a scare or two. Any expectation that a debut in this game at Newcastle's Utilita Arena on Saturday night was going to be a doddle disappeared within seconds of the fight getting underway.

Marshall is used to dealing with fists not feet. A front kick caused her to lose her balance immediately and although she quickly recovered, Vargas, purple belt in Brazilian jujitsu, twice took her Hartlepudlian opponent to the canvas. The fear was how Marshall would deal with such a scenario but she twice lifted herself up and punches were then traded in devastating flurries.

Vargas took some huge blows before the end came four minutes and 27 seconds into the first round - and then the fun started. Shields stepped into the cage but whereas plenty of shouting matches have come and gone before, this exchange was respectful.

"I am really proud of her, I'm happy for her. She got the job done, she fought through adversity," Shields said.

To recap, Marshall and Shields have a rivalry that goes back to the Hartlepool fighter winning when they clashed as amateurs. Shields won a thriller to become undisputed middleweight champion when they went at it again in the ring two years ago.

But another fight is inevitable.

"She knows I'm her biggest pay check," said Marshall.

But coming to an agreement on the details might not be easy.

"Claressa is the next fight we're going to get," said Hardy, from PFL.

"Claressa has been very complimentary of Savannah. I think Savannah got Claressa's respect tonight, not only what she can do with her hands but how she transitioned into MMA.

"The obvious thing is for Claressa and Savannah to fight next and I think that's what's going to happen. Claressa has a bit of boxing to deal with and then we'll get that fight locked in.

"My understanding is it's going to be this year towards the end of the year."

Shields - who has herself made the move into MMA - has a heavyweight boxing bout in July to first deal with.

Would the Marshall rematch follow?

"I'm going to let my team decide that," she said.

"Everything has to be strategically planned. I know from watching tonight I'm the better MMA fighter. We already knew Savannah had very strong hands. We'll do our homework and watch the fight without the crowd watching me and we'll see what my team think.

"Right now, I'm the better MMA fighter. She punches hard but I have some strong points that she doesn't have and she has some weaknesses I can take advantage of. The fights going to happen but I don't know when."

Shalom, who heads boxing promotional company BOXXER would rather see Marshall in the ring but was hugely impressed with her debut in the cage.

"I couldn't believe what I was seeing," he said.

"I was just thinking don't go down, don't go down then she's on the floor in 30 seconds. But she was able to manoeuvre herself, was strong and got herself back up.

"The big one has always been her vs Claressa. Whether that's MMA next or boxing I'm not sure. I'd want to do the rematch in boxing over three minute rounds when she has more time to break her down and find the gap.

"That's where I see the most exciting fight for her really. I'd fancy her chances at the bigger weight. I think she's much more comfortable at super middleweight. Let's see what she does at MMA."

While Marshall would like to get back between the ropes with Shields, "boxing politics" has previously prevented the rematch taking place.

"I just think PFL are making moves and Ben's not," she said.

"I'd like to get back into boxing but it's all about what happens next. I'm really not sure what comes next, I'd love to box before the end of the year so we'll have to see.

"I loved this. It's been a new challenge I didn't know I needed. I remember going on the floor and just seeing her knee fly past my head and thought Jesus Christ! But it was brilliant fun!"