By David Goldblatt
BBC Radio 4's Crossing Continents
Beitar Jerusalem may be top of the Israeli football league but the behaviour of its hard core fans is casting a shadow over their success.
Beitar fans awaiting the start of a game in Nazareth
It is half-time in an Israeli cup match between Ahi Nazareth and Beitar Jerusalem.
The atmosphere at the game is tense and the police presence is huge and heavily armed.
The former is the team of the largest Arab town in Israel. The latter has been the standard bearer of the political right in Israeli football for 70 years.
Once, when Israel was ruled by the Labor party and the trade unions, Beitar Jerusalem was the small team of the marginal and excluded. Now it is the most powerful club in the country, with the most volatile and extreme fans.
One group of around 30 fans make their way to the very back wall of the terraces. Some put on a yarmulke, others cover their heads with Beitar scarves. All begin to pray and sway.
I climb up the stand to try to find Guy Israeli, the leader of La Familia - the hard core organised fans of Beitar Jerusalem - who had agreed to meet me at the game.
Beitar win the game and the crowd sing: Death to Mohammed
I find him in the midst of the devotional. He is just a normal-looking bloke wearing black sweat pants and a yellow Beitar hoodie.
As the whistle goes for the second half and the crowd roars, he warmly clasps my hands and shouts:
"Ten generations. Five hundred years my family has been In Jerusalem. We come to pray, not because we are religious men, but because we are Jewish. We must show them that we are Jewish."
Beitar fans show the Arab supporters of Nazareth that and a lot more. They are ultra-nationalist and anti-Arab.
Beitar win the game and the crowd sing: "Death to Mohammed."
As the Nazareth crowd goes silent, they sing: "The muezzin has gone home."
No management at the club has dared to try and sign an Arab or a Muslim player
This is to be expected. In November 2007, on the 12th anniversary of the assassination of Prime Minister Yitzhak Rabin by the ultra-nationalist Yigal Amir, a minute's silence was held by every Israeli football crowd except Beitar.
La Familia sang songs in praise of Amir and the settlers in the West Bank.
The following month, they would join settlers groups in a flag-planting exercise on a proposed hilltop settlement in East Jerusalem.
No management at the club has dared to try to sign an Arab or a Muslim player.
Later in the week, I met Guy Israeli again. By day he is a tax consultant, but today he is preparing for Saturday's game.
He tells me how he founded La Familia, how he created its network of 3,000 supporters, and how, in the end, he chose La Familia over his wife.
I asked him to explain his prayers.
"This is my country," he says. "When I see one million Muslims praying in my country, it makes me nervous. The Arabs have 10, 11 countries, we have only one. And they want only this one.
"All the time the government says football makes peace. But we don't want peace, we want war."
But not everyone at Beitar wants war.
Israeli hip-hop artist Shannan Street started going to Beitar games in the early 1970s, and deplores the change in the crowd.
"Beitar always had a rightist fan base, but it was a Jerusalem fan base. Jerusalem is a mixed city and Arabs were always, always part of the deal. But in the last decade we started to get a lot of extreme rightists and fascists," he says.
"Its pretty disgusting and I know a lot of Beitar fans agree with me. It was the team that represented Jerusalem, not Israeli fascism."
Shannan recalls the story of an Arab opponent who died of a heart attack on the field. The whole Beitar team visited his family to show their respect.
Would today's Beitar do the same?
Perhaps, Shannan argues, Beitar's attempt to make it into the UEFA Champion's League will force the club's management to curb the public display of racism in the crowd.
He and his friends continue to go to their corner of the stadium.
La Familia attracts members from all walks of Israeli life
Similarly, David Frenkel, now a computer programmer in Israel's booming hi-technology sector, was once a huge Beitar's fan.
He crossed Europe to see them, travelling as far as the Faroe Islands. He loved the rough honesty and intensity of the fans.
Frenkel argues that the racism and xenophobia of the crowd was an inevitable outcome of Israel's ongoing conflict with the Palestinians.
However, the rising extremism of the last decade has forced him out.
"It's like sewer water. You can't criticise sewer water for stinking, but it doesn't mean that you have to bathe in it."
Commanding the mood
I met Guy Israeli for the last time before Beitar's game at Teddy Stadium in West Jerusalem. He was selling La Familia T-shirts out of the back of his car.
Members of La Familia joined us to talk. They were a mixed bunch: a Tel-Aviv teacher in her 50s, a middle-aged man with his children, young couples in matching club colours and a cluster of blonde spiky teens.
It is hard to gauge exactly, but La Familia is not just a bunch of adrenaline- fuelled teenagers.
Almost all of them argued that Beitar were an anti-Arab team and that was why they supported them.
Inside the stadium they were not a majority.
La Familia made up perhaps 20% of the audience, but they commanded the mood of the crowd and their chants were followed by almost every part of the stadium.
When a club official asked the fans over the PA system to just support the team, the volleys of abuse simply grew louder.
More recently, Beitar were just four minutes from clinching this year's title at home in Teddy Stadium, when their fans - lead by La Familia - invaded the pitch and made a restart impossible.
The Israeli FA has given that game to their opponents, docked the club two points and ordered the rest of their home games to be played without an audience.
Crossing Continents on Football in Israel will be broadcast on BBC Radio 4 on Thursday, 24 April at 1100 BST.