Lionel Messi says Barcelona continue to believe in themselves despite back-to-back La Liga defeats.
Barca have lost to Real Madrid and Real Sociedad in their last two league matches, while a 2-2 draw with Villarreal makes it a three-match winless run for the leaders.
The defending champions' lead at the summit has been cut to three points as a result, with Atletico Madrid in increasingly close pursuit.
Atleti are the opposition on Wednesday as European champions Barca look to turn their 2-1 first-leg advantage into a passage to the Champions League semi-finals.
And Messi insists Barca will not allow their season to collapse, posting on Facebook: "Our mindset remains the same. We work hard all year to have a chance of winning trophies at the end of the season.
"We continue to believe in ourselves."
Barca still remain on course to retain the treble they won last season, with Sevilla awaiting in next month's Copa del Rey final.