One team makes Barcelona more uncomfortable than any other and that is Valencia, who provided yet another upset against the odds to break Catalan hearts in the Copa del Rey final on Saturday evening.
Even despite two draws in LaLiga Santander, Barcelona were right to be concerned before the game given their past meetings, as these five examples of historic moments in clashes between the pair show.
Copa del Rey semi-final 1979: An unthinkable comeback
Barcelona won the first leg 4-1 at the Camp Nou and travelled to Mestalla relaxed and expecting a formality, but Valencia achieved the impossible with a 4-0 win thanks to the decisive goal in minute 91 which took them to a final where they beat Real Madrid.
1987/88: Valencia's top flight return and Terry Venables' dismissal
In 1986, Valencia's greatest fears were confirmed at Camp Nou as they were relegated with one game left to play, but on their return a year later Carlos Arroyo made the difference with a 1-0 win which led to the sacking of Terry Venables.
1991/92: The first to beat Johann Cruyff's dream team
Another Copa del Rey semi-final between the two clubs looked set to produce another comeback, with Barcelona overcoming a 2-0 first leg defeat at Mestalla to lead 3-0, only for the tie to end 4-3 and eliminate the all powerful team of Johann Cruyff.
1997/98: Louis Van Gaal's disbelief as 3-0 turned to 3-4
Louis Van Gaal's Barcelona took on Claudio Ranieri's Valencia racing to a 3-0 lead after 70 minutes, only for an incredible 20 minute turnaround to see Valencia run out winners 4-3 thanks to Ariel Ortega's late strike.
1999/2000: Champions League semi-final
Barcelona were clear favourites to make it to the final in Paris but Valencia decided the tie with a convincing 4-1 win in the first leg, which Barcelona could not overcome despite a 2-1 win in the return fixture.