S.C.U Torreense, a second-tier Portuguese club based 35 miles north of Lisbon, will welcome Sunderland in the Europa League on Thursday in a fixture that continues one of European football's most improbable stories this season.

Torreense earned their spot in the competition by winning the Taca de Portugal in May, defeating Sporting 2-1 in the final thanks to an extra-time penalty from captain and Cape Verde international Stopira. It marked the first time in the competition's history, dating back to 1938 under its current format, that a second-division side had lifted the trophy.

The achievement is especially remarkable given that Torreense play in a division where they face the reserve teams of Sporting, Benfica and Porto, while missing out on promotion to the top flight themselves after a 2-0 aggregate defeat to Casa Pia in a play-off. The club have not featured in Portugal's top division since the 1991-92 season.

Despite their modest status, Torreense have already made a mark on the European stage, picking up three points from their opening game by beating Norwegian outfit Lillestrom. Their European schedule also includes matches against Ferencvaros, Ararat-Armenia, Celtic, Real Sociedad, Lech Poznan and Olympiacos before the end of January.

Andre Sabino, the club's director of football and CEO, described the campaign as a defining moment for the organization. "This is a landmark moment," he told BBC Sport. "It is something extraordinary for Torreense. These are clubs with huge histories, strong identities and enormous European experience. To be able to share the same competition and compete against them is a privilege. But we don't want to simply participate. We want to compete."

Portuguese football journalist and former Benfica goalkeeper Jose Delgado called the run historic. "I thought that Torreense could go through the Europa League with no points," he said. "The truth is that they already have three points and that is something. It's something that I don't think will ever happen again in Portuguese football. But Torreense has this."

Because their regular home, the 2,431-capacity Estadio Manuel Marques, does not meet UEFA's stadium requirements, Torreense will host Sunderland at the Municipal Stadium in Leiria, roughly 47 miles from their usual base. Sabino acknowledged the inconvenience but praised the response from supporters. "Our supporters and our people are what make a home, regardless of the kilometers," he said. "They understand that this is a historic moment for Torreense and they want to experience it with us."

Qualification for the league phase has also brought significant financial benefits, guaranteeing at least 5 million euros (£4.2m), with the club having already pocketed 630,000 euros (£533,000) from their win over Lillestrom. Sabino said the club intends to use the windfall carefully. "Our objective is not simply to spend more because we have more resources," he explained. "We want to invest intelligently, strengthen the structure of the club and create conditions for sustainable growth."

To prepare for the step up, Torreense have brought in 19 new players from 10 countries, including France, Greece, Spain, Serbia, Brazil, Denmark, Morocco and Germany, leaving just four Portuguese players in their 32-man squad. The adjustment has coincided with a difficult start domestically, where Torreense have won only one of their first seven league matches this season.

Delgado suggested the European adventure, while unlikely to transform the club's local following given the dominance of Portugal's traditional giants, could still attract outside interest. "Maybe this presence will make some investors look at them in a different way and put some money in the club," he said.

Based on reporting from BBC Sport.