Jailed militant Islamists in Nigeria have taken up football as part of a government de-radicalisation scheme. The BBC's Will Ross met some of them.
It was not your average kick-around. The six-a-side game was inside the high walls of a Nigerian prison and the players wearing the smart green and yellow strips are all accused of being members of militant group Boko Haram.
The early-morning training session is part of a de-radicalisation programme. The jihadist group bans all sport so it is a sign of progress that these men in their 20s and 30s are playing at all.
"These are people who have a wild concept about life, who look at killing as a very easy something, so we have to work on them to change that ideology [and] for them to have respect for human life," says Emmanuel Osagie, a member of the de-radicalisation team.
"Initially the participation was not encouraging but when they saw their colleagues coming back excited and feeling fulfilled from the sport it brought the others out," he says.
The man trying to teach some teamwork skills is in no doubt that this is helping change their outlook.
"Before, they didn't tolerate others. There is supposed to be a spirit of sportsmanship and it is this spirit that makes them normal and reduces their radical ideology," says Abioye Adeshina, who is in charge of sports at the prison.
A loud evangelical church service was taking place right next to the pitch - a coincidence, I think, rather than a conscious effort to instil religious tolerance in the 45 inmates who are referred to as "De-radicalisation Interest Clients".
"When I came here, I wouldn't take orders from the prison staff. I was always arguing with them. I didn't consider them to be human beings," says a stocky man in his mid-30s shortly after pulling off a few saves as the yellow team's goalkeeper.
The man, who cannot be named for security reasons, tells me he was arrested at a checkpoint four years ago after banks and police stations were attacked in the northern Bauchi state. He denies any involvement in that violence but admits to being a Boko Haram member.
"I love my religion and when [former Boko Haram leader] Mohammed Yusuf came preaching to us, I started following him to the villages and towns where he was preaching," he said, appearing relaxed and comfortable being interviewed.
'Starting life afresh'
Still awaiting trial, he says he was never armed and does not support the violent nature of the group.
Mr Yusuf was killed in police detention in 2009 and when hundreds of his followers were also killed by the security forces during an operation in Maiduguri city in Borno state, the group became a far more radical, murderous force.
Boko Haram at a glance
- Founded in 2002, initially focused on opposing Western-style education - Boko Haram means "Western education is forbidden" in the Hausa language
- Launched full-scale military operations in 2009
- Thousands killed, mostly in north-eastern Nigeria, abducted hundreds, including at least 200 schoolgirls
- Joined Islamic State, now calls itself "West African province"
- Seized large area in north-east, where it declared caliphate
- Regional force has retaken most territory this year
The prisoner, who is from Borno, says he had long wanted to fight a holy war and had even once joined al-Qaeda with the intention of fighting in Afghanistan.
Despite his long-held views, he says the de-radicalisation programme in the prison has changed his outlook.
"When the imams came, I thought they were hypocrites and I would abuse them. But despite my aggression they persevered and when I realised they were giving me respect, I started listening to them.
"As I talked with the imams, they convinced me that all that I had been doing was a mistake.
"I shed tears when I realised I had ruined my life. All my younger brothers are married with children but I'm not married and I have no child. So now I'm looking at how to start my life afresh."
On the other side of the prison, past the open-air barbers, are the newly built classrooms where teachers and psychologists are helping the prisoners learn new skills, including jewellery-making and basic electronics.
A group counselling session is also underway, focusing on the dangers of drug abuse.
This treatment is certainly in stark contrast to the way human rights groups say Boko Haram suspects have been treated in the past.
Amnesty International says that 7,000 young men and boys have died in military detention since 2011.
Last year Nigeria's then-national security advisor announced a new counter-terrorism strategy, in addition to the military option.
The de-radicalisation programme is part of this "soft approach" to fighting terrorism. Those interacting with the inmates get vital clues which shed light on why extremism has found fertile ground in Nigeria.
"The biggest surprise for me was how inadequate their level of ability to think and reason logically was," says Dr Fatima Akilu, a psychologist who designed the programme.
She says they did not have the skills to counter the narrative that they were being fed by a charismatic preacher, and educational reform in Nigeria's schools is urgently needed.
"We've got to teach religion, both Christianity and Islam, a lot better than we have been doing. A lot of kids just memorise the Koran, so we've got to understand the meaning of what they are memorising and we've got to do a lot better in terms of tolerance of other faiths," says Dr Akilu.
"So when someone says to you: 'My religion says that you should hate someone from another religion,' you can actually counter that."
In one of the prison classrooms there is a very basic maths lesson for the men accused of belonging to the sect, which has been attacking schools, killing and kidnapping students under the belief that Western education is sinful.
In the mosque there is religious teaching for the men who had believed the Koran justified Boko Haram's violence.
The second inmate I am allowed to interview tells me he joined the group before it took up arms.
"Ever since my childhood I have hated three things; lies, cheating and oppression. And those things became the order of the day for the government," says the bespectacled inmate.
"So when this man came claiming to lead us towards a just and equitable society where those three things do not exist, I decided to join," he says.
'Dressing up as women'
He tells me he spent a lot of time and even shared his home with Abubakar Shekau, the man who turned Boko Haram into an extremely brutal force after he succeeded Mr Yusuf.
He says Mr Shekau is impossible to reason with.
"I knew him to be very obstinate. Even if someone is wearing a black shirt he can say it is white and you will never change his mind. His leadership is what has made it a violent and extremist group - they don't have regard for human life at all."
As we were not allowed to speak to the more recently captured suspects, I asked if he had heard from them why girls as young as 10 were being used as suicide bombers.
"When someone is hell-bent on doing something, they will go to any lengths to achieve that goal. So when the military was preventing some of the attacks they turned to plan B. Instead of men dressing up as women to carry out the bombings they decided to use girls and women," he replied.
Although the staff working in this prison say they are seeing fast results, it may take years to de-radicalise some of these men.
But the hope is if they can change, they will be able to help turn others away from violence and even tempt jihadists to give up the rebellion.
We will never know where northern Nigeria would be now had this approach to the conflict been pushed on a greater scale years ago.