(CNN) -- Sporting continued their worst start to a season since the Portuguese league was founded in 1933 as they lost 3-1 at home to Benfica, with fans of the Lisbon club further suffering as their city rivals went top of the table.
Already knocked out of the Portuguese Cup and the Europa League, Sporting are now 18 points behind Benfica and second-placed FC Porto, who both boast 29 points, and just four points off the bottom of the Primeira Liga.
Traditionally one of the big three of the Portuguese game, Sporting have - along with Benfica and Porto - won all but two of the 78 titles in the country's football history.
Yet a club that won its last league title in 2002, and which last competed in the Champions League three years ago (when suffering a humiliating 12-1 aggregate defeat to Bayern Munich), is now in greater danger of suffering the first relegation in its history.
Despite leading at the break after a fine Ricky van Wolfswinkel goal, Sporting surrendered in the second half as striker Oscar Cardozo had a hand in all three goals -- forcing two own goals either side of netting an 81st-minute penalty to preserve the Eagles' unbeaten run.
After Dutch defender Khalid Boulahrouz was sent off for saving a goalbound effort with his hand, Paraguayan Cardozo slid home a cool penalty to spark an exodus for Sporting fans from the Estadio Jose Alvalade.
Belgian coach Franky Vercauteren only took charge of Sporting, who won the Cup Winners Cup in the 1960s and lost the Uefa Cup final in their own stadium in 2005, one month ago -- becoming the club's seventh coach in just four seasons.
"In the second half, Sporting had great difficulty in keeping up with our game, because we always had a strong and intense style of play," Benfica coach Jorge Jesus told his club's official website. "We beat a great team, one that will improve."
While Benfica's Eagles regained confidence after last week's Champions League exit, Sporting's current predicament makes a mockery of the team's stated ambition upon its founding -- which was to be "a great club, as great as the greatest in Europe."
Elsewhere across the continent, Lazio extended their unbeaten league run to five games after drawing 0-0 at Bologna -- a result which left the Rome side, who lost striker Liber Kozak to a late red card, three points behind third-placed Napoli in Serie A.
Earlier, Udinese climbed three places to eighth in the table after winning 2-0 at Sampdoria --as goals from Danilo and Antonio Di Natale took the Udine side just behind AC Milan in Serie A.
In the English Premier League, Fulham beat Newcastle United 2-1 at home to end a run of seven games without a win, as Steve Sidwell and Hugo Rodallega scored either side of a dipping Hatem Ben Arfa strike for the visitors.