Barcelona's 26-game unbeaten league run was ended abruptly on Sunday at the new San Mames Stadium when Athletic Club's answer to Leo Messi, Iker Muniain, scored in the 71st minute.
Could the reason for the defeat be the absence of the aforementioned Argentinian? Could it be that Bilbao happened to put in an excellent performance that deserved three points, regardless of Barca's personnel issues?
It's all down to what Spanish newspaper AS is calling "The Curse of the Catalan Flag" (in Spanish).
The Blaugrana have dropped points on the last five occasions they have worn their away strip—a tribute to the red and yellow stripes of the Catalan flag—which includes defeats against Athletic Club and Bayern Munich, and draws with Osasuna, Atletico Madrid and Milan.
While Barca fans dread the next outing in their away colours, here are five other jinxed strips...
When Manchester United found themselves 3-0 down against Southampton at half-time at the Dell in April 1996, Sir Alex Ferguson decided to blame the club's grey strip, claiming the players "couldn't pick each other out."
They emerged in the second half wearing blue and white and managed to pull a goal back, but it wasn't enough to save an embarrassing afternoon. Understandably, thousands of parents who shelled out for the grey kit were miffed when it was consigned to the history books.
They say it is unlucky for a black cat to cross your path, but in Milan, it's a black kit that vexed the Rossoneri.
This is in spite of the fact that they actually won the tie 4-3 on aggregate and won their 16th Serie A title in 1998/99 wearing the colour in a victory over Perugia.
Nigeria fans kicked up a fuss prior to the 2013 Africa Cup of Nations when it was revealed they would be taking on reigning champions Zambia and Ethiopia in their "unlucky" white kits.
The Super Eagles had lost the AFCON finals in 1998 and 2000 to Cameroon while wearing white, hence the trepidation. "I hope this is not another ploy by CAF to stop Nigeria from winning the Nations Cup," a very cynical Nigeria fan told mtnfootball.com.
Of course, Nigeria needn't have worried. They drew with Zambia and beat Ethiopia, going on to win their third Nations Cup.
England ended a relationship with Umbro that had lasted more than 50 years when they sported a Nike kit for the friendly with the Republic of Ireland in May 2013.
Over the summer, there were concerns that the kit was cursed: The senior team could only draw its first two friendlies (Ireland and Brazil), the U21 lost all three of their European Championships matches in disastrous fashion and the women's side were winless in their first four outings wearing it.
With a little perspective, this curse seems premature as the senior side are undefeated in competitive matches with a swoosh on their chests, winning three of four. (Of course, don't rule out a cursed kit as being a scapegoat for a pitiful outing in Brazil next summer.)
Approaching the 2009/10 Christmas break, the bloggers at footyfactor.com noticed a pattern: Chelsea were undefeated in their blue home kit but lost on all four occasions they wore their navy blue striped away shirt with neon piping.
Carlo Ancelotti's side only wore the shirt again that season at Ewood Park, where they were held to a draw by Blackburn. On visits to Everton and Portsmouth, they wore the white third-choice strip instead.
Chelsea won the league that season regardless, but the navy kit was dumped for black and orange in 2010/11.