Glasgow, Scotland - Scottish champions Celtic play host to their Israeli counterparts Hapoel Be'er Sheva on Wednesday night in a crucial UEFA Champions League play-off match. This is football's most illustrious club competition, and the stakes are high. Qualification for the group stages means riches of up to 30 million pounds ($38m), as well as the prestige and glamour of mingling with Europe's elite.

However, all eyes won't just be on the 22 players on the pitch on Wednesday evening. Instead, much of the build-up to the game has been dominated by what is expected to take place in the stands.

Many Celtic fans have long identified with left-wing causes, among them the Palestinian struggle. The flag of Palestine is seen flying at games the club plays, and the match with Hapoel Be'er Sheva will be no exception.

The hype around the fixture has already led to the Israeli embassy in London warning Celtic fans against any displays of solidarity. The Israeli embassy in London however, told Al Jazeera that they are "certain that the team and the Israeli fans arriving for the game will receive a warm welcome in Glasgow". But that faith seems to be misplaced.

A Facebook event titled "Fly the flag for Palestine, for Celtic, for Justice" has over 1,000 people attending, with advice posted on where fans can pick up Palestinian flags in Glasgow.

According to Scottish historian Tom Devine, this sense of solidarity with a people thousands of miles away has its roots in the Irish identity of much of the Celtic support.

"It's [got] to do with the sense that the Irish Catholics in Scotland have of being underdogs over several generations," Devine told Al Jazeera. "There is a strong sense of history among that community, even though it's now third-, fourth- and fifth-generation Irish."

"Part of their sense of communal identity is that sense of grievance about what was done in the past. People who are Irish nationalists will always tend to support independence movements that they believe to be based on historical justice," Devine says.

"The situation in Palestine is a classic example of land that is being taken from people who lived there for generations. It chimes in with the course of Irish history."

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The link has got Celtic into hot water with the football authorities in the past. The club was fined 16,000 pounds ($20,750) by the Union of European Football Associations ( UEFA) after fans flew Palestine flags during a game against the Icelandic side KR Reykjavik. The game took place at the same time as the Israeli army's "Protective Edge" operation in Gaza, which left more than 2,200 Palestinians and at least 73 Israelis dead.

Courting controversy

The main protagonists on that occasion were the group of ultra-loyal Celtic fans, or "ultras", known as the Green Brigade, a group set to take centre-stage again. A member of the group told Al Jazeera that they "show their continued support for Palestine at every match … and the match against Hapoel Be'er Sheva will be no different".

The Green Brigade, who identify as left-wing and Irish Republican, have previously courted controversy for displays that protested against British wars abroad as well as a banner remembering Bobby Sands, a member of the Provisional Irish Republican Army who died while on hunger strike in 1981. And when hundreds of Palestinians were on hunger strike in Israeli jails in 2012, the group unfurled a banner reading "Dignity is more precious than food".

Less widely known, though, is the extensive fundraising work of the group to help bring Palestinian youth to the UK to take part in football tournaments and cultural tours. Numerous members of the group have also visited the occupied West Bank.

"From our work with Palestinian groups and visits to Palestine, we know the importance of international solidarity and the positive impact that it has for those living in occupied Palestine," a Green Brigade member, who wished to remain anonymous, told Al Jazeera

"We know that our actions send a message to Palestinians that their struggle is not forgotten.

"Football and sport do not live in a vacuum, separate from wider society," the Green Brigade member explained. "It didn't during the 1980s when the authorities excluded apartheid South Africa from football … nor should it now. Israel must be held accountable for its oppressive and brutal 68-year occupation of Palestine."

Separation of politics and sport

The South African example inspired the Boycott Divestment and Sanctions movement, which was launched in 2005. The Red-Card Israeli Racism branch of the campaign argues for a suspension of the Israeli Football Association's membership of FIFA and UEFA until the country "observes international law and respects the human rights of Palestinians".

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Hapoel Be'er Sheva's chief executive Alona Barakat has been quick to emphasise the inclusive nature of the club's signing policy, in contrast with some football clubs in Israel, such as Beitar Jerusalem, who don't allow Arabs on their teams.

"There is no place for racism or intolerance in [football]," Barakat told The Times of Israel. "Our team has Jews, Arabs, foreign Christians, and we sign players according to merit, not their ethnic or religious background."

But critics question if even football clubs can be separated from the political context in a place like Israel. The Turner Stadium where Be'er Sheva play lies just 20 miles from the besieged Gaza Strip, home to 1.8 million people living in desperate conditions. Indeed, the city of Beersheba itself was once the Palestinian town of Bir al-Sabe' before its Palestinian inhabitants were forced out during the war of 1948.

The restrictions put on Palestine's footballers are also often pointed to by campaigners.

The national stadium has been bombed. The headquarters of the Palestine Football Association (PFA) has been raided. Players, along with most other Palestinian athletes, are routinely detained or refused visas or permits to travel with the national team.

Two years ago, 19-year-old Jawhar Nasser Jawhar, and 17-year-old Adam Abd al-Raouf Halabiya had their careers ended when they were shot in the feet by Israeli soldiers at a checkpoint. Others have been killed in missile strikes, such as former Palestinian football star Ahed Zaqqut in Gaza.

In response to the violations, the PFA called for Israel's expulsion at FIFA's annual congress last year. The motion was withdrawn at the last minute, but it was an unwelcome episode for the Israelis.

As pictures of Wednesday evening's game are beamed worldwide, it could prove to be another awkward occasion for Israeli football. Celtic, too, will be less than happy to be hit with another UEFA fine for breaching rules on political statements.

But as the fans have argued before, some things are more precious than money.

Follow Liam O'Hare on Twitter @liam_O_hare