Last weekend Barca missed the chance to claim a club-record seventh successive win to start a Primera Division season when they were held to a goalless draw by Valencia, and then on Tuesday they suffered a shock Champions League defeat to Rubin Kazan.

The last time holders Barca lost in Europe was in December when a much-weakened team were beaten by Shakhtar Donetsk in a dead rubber at the Nou Camp, but this time Pep Guardiola's men were virtually at full strength and were downed 2-1.

That was Barca's first competitive defeat since May and left the team with a fight on their hands to progress through to the last 16 of the Champions League, but Iniesta believes his side will bounce back even stronger.

"It would be unfair to doubt this team after all it has done," he told Catalunya Radio.

"Not winning hurts everyone and I wish we could win every game 5-0. The team is on a good path but when the results don't come then you know there will be lots of opinions why.

"The confidence remains the same and we are going to continue working as we have been doing.

"This stumble has to make us stronger. Now we must think about winning on Sunday against Zaragoza."

Barca, who also lost Dani Alves to an injury against Rubin that could see the flying full-back out for up to a month, are not the only Spanish side nursing a European hangover, though.

Just 24 hours after Barca were beaten, both Real Madrid and city rivals Atletico suffered Champions League misery as they lost to AC Milan and Chelsea, respectively.

Madrid surrendered top spot and their 100% start in Group C after going down 3-2 to Milan, which was their second competitive defeat of the season having lost to Sevilla earlier this month.

Like Iniesta though, Madrid midfielder Royston Drenthe has played down the defeat and is already looking ahead to this weekend's league trip to Sporting Gijon.

"It's not a crisis, we can also lose games," he said in AS.

"We will play in Gijon and then against Milan over there. Why talk of crisis? We are fine in the league and the Champions League.

"The people don't understand that the Madrid players are people and that we can also lose. This is football, anything can happen."

Despite their recent setbacks, Barcelona and Madrid are still healthy placed both in La Liga and the Champions League, but the same cannot be said of Atletico.

Their 4-0 mauling by Chelsea has left them with just one point from three Champions League games, while they have only picked up one win from seven domestic matches, leaving them in 15th place.

It also looks set to cost coach Abel Resino his job, with Spanish media suggesting Michael Laudrup is being lined up to take charge ahead of this weekend's home match with Real Mallorca.

Another coach who looks to be in big trouble is Villarreal boss Ernesto Valverde, whose side slumped to the foot of the standings last week after losing to Xerez in a clash between the two bottom clubs.

Villarreal face a similar battle this weekend as they take on 19th-placed Malaga.

Elsewhere, third-placed Sevilla, who were the only Spanish team to enjoy a Champions League win after downing Stuttgart 3-1, host Espanyol and fourth-placed Deportivo La Coruna meet Real Valladolid.

Also, Tenerife host fellow promoted side Xerez, Athletic Bilbao go to Getafe, Valencia are at Almeria and Racing Santander host Osasuna.