Barcelona's patchy form continued as they were unable to break down a diligent and bold Slavia Prague side at home and were held to a 0-0 draw in the Champions League on Tuesday.
With Luis Suarez injured, Barca lacked a cutting edge in attack and visiting goalkeeper Ondrej Kolar produced an admirable display to shut out the Catalans, thwarting Lionel Messi and Sergi Roberto from close range in the second half.
Messi also struck a post in the first half and Barca later had an effort by Arturo Vidal ruled out for offside against the Argentine.
"Playing like this it's difficult to see us winning the Champions League," said Barca defender Gerard Pique. "We had chances to score but the ball wouldn't go in. Results aren't going our way in these last two games, and when you go two games without winning at Barca the fans expect more because expectations are so high.
"It's difficult to say right now but there have been times when we've not looked good in the past and we've ended up winning trophies. With Luis Enrique it looked like things weren't working for the first six months and then we won the Treble.
"I would ask for a little patience. I know the fans want more, we understand that, but we're working hard to find the solutions. Not so much in terms of results, but in terms of how we're playing."
Barca lead the group on eight points after four games, while Slavia are bottom with two.
The Czechs, who were unfortunate to lose 2-1 at home to Barca two weeks ago, made a bright start and nearly took an early lead with a heavily deflected shot which was repelled by the Catalans' goalkeeper Marc-Andre ter Stegen.
They did manage to find the net at the end of the first half but the goal was disallowed for a clear offside.
The visitors had bright spells in the second half although they did not manage to test Ter Stegen further, and angry boos and whistles rang out around the Camp Nou at full-time.
"It's a difficult moment for us but the fans have the right to express how they feel and it's up to us to deal with it," said Barca defender Clement Lenglet.
"We knew Slavia were a dangerous opponent who had quality and we were not taken by surprise by them. We suffered at various stages of the game.
"We don't have any time to sit around and get worried, we have to keep working and play every three days. We're going to turn this around."