How do you spend 21 days locked up in isolation with a Brazilian model? Easy. You teach her how to play cricket.

Coco Cuhna made the mistake of suggesting to her cricket coach boyfriend that it might be fun to see if he could show her how to bat when she saw him whacking a few tennis balls into his new pop-up net.

'I was joking… he took it very seriously,' she tells The Mail on Sunday. 'I thought 'Oh my gosh, what have I got myself in for!'

Since then, for 25 minutes every day, Coco has been learning to bat. From finding out the basics of how to swing it to being able to drive, cut and pull.

Her boyfriend Gio Colucci is director at The Cricket Academy in Cape Town, South Africa and has coached the likes of England batsman Tom Wesley, Derbyshire captain Billy Godleman and Ben Curran, brother of England duo Tom and Sam. Now, he's got a Brazilian model on his hands.

'I had never had any contact with cricket before, I never even knew about it before I moved to South Africa,' says Coco.

Today (Sunday) is the 15th day of the challenge. She's actually starting to enjoy herself.

'At the beginning, I was like why did I do that,' says Coco. 'The first day was the worst: I didn't know how to hold the bat, didn't know the positions, nothing… I thought God this is going to be so boring! But when you start to hit balls, I started to get a bit more excited. I am very competitive. I can't remember which day it was that I just wanted to break the bat. I felt like a tennis player who just wants to smash their racquet. But Gio would always calm me down and tell me I could do it.'

Gio has been impressed, too. 'I've seen a massive improvement,' he says. 'I never doubted that we would be able to do it but she is doing it far faster than I thought she would. She has started to really cane some drives! It is great because it reaffirms how simple you can make things if you know how to communicate the fundamentals.'

Any arguments yet? 'No! Not yet,' says Coco. 'Sometimes he tells me to do something and I am like 'I am doing it properly' and he says 'you're not'. I am a little bit stubborn. Sometimes I want to kill him but it's all good!'

Coco has been modelling since she was 14, graduated in journalism and worked briefly for a press agency in Sao Paulo. Now 31, she also runs her own Brazilian food company which specialises in tapioca, a starchy plant from north Brazil.

The two met at a pacha party on Grand Beach in Cape Town six years ago. Coco had come over to visit her sister who lives in South Africa. Having returned to Brazil, she returned for her sister's wedding 18 months later where she met Gio again. The two have been together ever since.

'I took her down to Newlands for a Test match about two years ago at Newlands, as part of Hashim Amla's army. All dressed up, drinking beer.…after about half an hour she said it was boring and was going home!'

Isolation rules in South Africa are even stricter than in the UK. Gio and Coco are only allowed to leave the house to buy groceries or go to the doctors.