By David Latona and Michael Francis Gore

MADRID (Reuters) - In Madrid's working-class neighbourhood of Vallecas, a plucky LaLiga team dwarfs local juggernauts Real Madrid and Atletico in popularity: Rayo Vallecano, which in May turned 100 as simmering political conflict between the fans and owner reached a boiling point.

The humble squad snagged a 3-3 draw against Real in the centenary year's last home match on Saturday - underscoring Rayo's "Giant-slayer" nickname earned after their triumph in the next-door rivals' first league duel in 1977.

Early in the game, the Estadio de Vallecas roared in unison a recurrent chant demanding Rayo's chairman "leave already", led by the team's left-anarchist ultras, the Bukaneros (Buccaneers).

Raul Martin Presa, who bought 96% of debt-ridden Rayo's shares in 2011 for just $1,000, can boast of helming the club through arguably its finest run, remaining in the top flight for 10 out of the past 14 seasons on shoestring budgets.

But fans complain of management's dismissive attitude towards them and lack of investment. Presa's prioritisation of financial stability clashes with fans' anti-establishment bent and emphasis on social causes.

The club declined to comment on the various points of contention.

Fan pressure derailed a 2017 loan deal for Ukrainian striker Roman Zozulya over photos of him allegedly featuring far-right symbols. Upon Zozulya's 2019 return to Vallecas with another team, chants calling him a "Nazi" led to the match being abandoned at halftime - a first in Spanish football.

Many supporters are also frustrated by the occasional presence of politicians from the far-right Vox party in the VIP box.

DISPUTED STADIUM MOVE, ANALOGUE SALES

In July, supporters' association Plataforma ADRV accused Presa of "laziness, incompetence and contempt" by ignoring talks on centenary celebrations and replacing the iconic diagonal red stripe on the season's kit with the number 100, if stylised as the Rayo's namesake lightning bolts.

Presa's insistence that Rayo needed a new stadium to meet modern standards of safety, comfort and profitability saw backlash from Vallecans who feel the nearly 50-year-old arena is essential to their identity.

The stadium lacks stands in its north end, instead occupied by pitchside apartment buildings whose residents have a privileged view of the action from their balconies.

One resident, Julia Hernandez, told Reuters while hosting a derby watch party for her granddaughter and friends, she opposed a move as the venue livened up the neighbourhood.

After multiple protests, the Madrid region - which owns the stadium - has approved initial refurbishment works at the 14,000-seater venue, though its future remains unclear.

Long queues are common outside the gate, as Rayo is the only top-flight club that doesn't sell tickets online.

"People are working and can't buy them in person," bemoaned Emma Calderon, 20, as she shivered in line.

But Glaswegian expat and decade-long Rayo season ticket holder Kieran McIvor said the fandom's culture beyond big-money football was what attracted him, jibing with the values of his beloved Celtic FC.

"You need to be supportive of teams like this that care about the community, about local people, and are doing something significant," he said.

(Reporting by David Latona and Michael Gore; Additional reporting by Ana Beltrán; Editing by Christian Radnedge)