Four years on from languishing in Portugal's third tier, Famalicao sit atop the Primeira Liga and face Porto on Sunday in a match shaping up as a clash of the brash young guns against the old order.

Famalicao, one point ahead of Porto in the table, are Portugal's upstarts posing a genuine and remarkable threat to the established elite.

Behind Famalicao's swift rise from obscurity lies a long history going back to 1932 when the club from Vila Nova de Famalicao, a town in the north of Portugal, played their very first football match against Porto.

But after 87 years of divergence, in which Porto have won 28 league titles, four of them in the last decade, and the Champions League in 2004, the two clubs reunite this weekend on a more even footing.

At the heart of Famalicao's surge to prominence is the dual-pronged leadership of Portuguese super-agent Jorge Mendes and an Israeli billionaire.

"Not even in my wildest dreams could I have imagined that we would be leaders of the Portuguese championship," admits Ramiro Carvalho, who has supported Famalicao for some 40 years.

The 64-year-old, wearing the club's navy blue jersey, had just travelled 350 kilometres (220 miles) to see his team win 2-1 away at Sporting Lisbon last month, a victory that thrust Famalicao above both Porto and defending champions Benfica.

Ten years ago, they had sunk to the fifth tier but steadily they clawed their way back and had just finished 14th in the second when Israeli oil magnate Idan Ofer accepted the challenge offered by Mendes, his friend, in June 2018.

The billionaire, who also owns a third of Atletico Madrid, saw in Famalicao's industrial city of 130,000 inhabitants, an investment opportunity, even as its team sat at the bottom of the second division.

A year later, the club had been promoted to the top flight after a 25-year absence and in early September, Ofer increased the share of his holding company, Quantum Pacific, in the club from 51 per cent to 85 per cent.

Perhaps even more important than Ofer's cheque book has been Mendes' book of contacts along with his agency Gestifute, whose portfolio includes Cristiano Ronaldo, Jose Mourinho and the young Portuguese sensation Joao Felix, who left Benfica for Atletico Madrid last summer in a deal worth 126 million euros.

"Famalicao has a privileged relationship with Jorge Mendes," said Famalicao's general director, Miguel Ribeiro, in an interview with the Portuguese weekly Expresso.

"Gestifute had followed the club and when Quantum Pacific joined as a partner, they celebrated it like a wedding.

"Our ambition is for Famalicao to play at the highest level of Portuguese football and when I say this I'm not talking about staying up."

Mendes' influence at Wolverhampton Wanderers in England has helped the team become an established Premier League club with aspirations this season to qualify for the Champions League.

In a similar way, his finger prints are dotted over the transfer dealings of Famalicao, many of whose signings have been either linked to Gestifute or European clubs in which Mendes has a hand.

Talented players from Benfica, Atletico, Valencia, Wolves and West Ham came on loan, such as Argentine defender Nehuen Perez, who was nominated last month for the Golden Boy award.

"We are aware of the importance of Jorge Mendes within the club. Without him, Famalicao could not bring in those players," says Francisco Fontao, a 37-year-old supporter.

Despite its heady heights in the league, Famalicao's stadium harks back to a bygone era, owning just 5,500 seats that will be expanded to 7,000 in 2021, after an investment of around 8 million euros.

It is a reminder that there is work to do and coach Joao Pedro Sousa is determined to keep his players grounded.

"Our goal is survival and I want to ensure we don't think about anything else until we achieve it," he said.

But should they beat Porto, then Famalicao might think anything is possible.