Real Sociedad have made a habit of defeating La Liga's elite sides this term, but face a tough test at Real Madrid on Saturday.
Real Sociedad's chances of doing a first league double over Real Madrid since 2004 have received a significant boost with Cristiano Ronaldo, La Liga's leading marksman, set to miss out through suspension.
David Moyes' Sociedad travel to Santiago Bernabeu on Saturday looking for a rare double against the European champions.
Of Sociedad's five league wins this season, three have come against Real, Barcelona and Atletico Madrid, highlighting their ability.
And while Moyes was not in charge when Sociedad beat Real Madrid 4-2 in August, his players are sure to hold fond memories of a clash that saw them come from two goals down to win.
Ronaldo also missed that clash, with fitness issues preventing him from appearing in San Sebastian.
His absence on this occasion comes after the FIFA Ballon d'Or winner was suspended for two matches for kicking out at Cordoba defender Edimar and then raising a hand to strike him in the face last Saturday.
Ronaldo lost his temper after failing to make an impact in the clash against the Liga strugglers and was given his marching orders with eight minutes left, although there was still time for Gareth Bale to net an 89th-minute penalty in a 2-1 win.
Having scored 36 goals in 31 appearances in all competitions this season, Ronaldo will undoubtedly be a massive loss, but his absence could pave the way for promising youngster Jese Rodriguez to be involved from the start.
Madrid, also without Luka Modric (thigh), are not out for revenge against Sociedad, with midfielder Isco saying this week they preferred to focus on themselves.
It remains to be seen whether Madrid will give new signing Lucas Silva his debut after the 21-year-old joined from Cruzeiro on Monday.
The highly rated Brazilian joins Martin Odegaard's as the club's major January signings.
While Madrid are preparing for the future, Sociedad will look to the past for inspiration to beat Real twice in the league since 2004, following up a 1-0 home win with a 4-1 success at the Bernabeu in May of that year. Playing on both occasions for Madrid were Brazil great Ronaldo, Raul, Luis Figo and Roberto Carlos.
Madrid have won nine of the last 11 meetings between the two sides, but maybe Moyes can look to his impressive record against Carlo Ancelotti for inspiration.
The Scot's Everton side beat Ancelotti's Chelsea in both the 2009-10 and 2010-11 Premier League seasons, while they also dumped them out of the FA Cup in February 2011.
Ancelotti was sacked by Chelsea after their league loss to Everton in May 2011.