Holders Barca had not suffered a defeat in Europe since last December, when, having already qualified for the last 16, a much-weakened side were beaten by Shakhtar Donetsk, but that run came to an end last night against a hard-working Rubin side.

The result has made things extremely tight in Group F, with Barca now level on four points with Rubin and Dynamo Kiev, while Italian giants Inter Milan are just one point behind, and with two of their final three games involving difficult winter trips to Ukraine and Russia, Guardiola knows his men have a fight on their hands to progress.

He said: "The group has become very tight, and we all have a chance to get through to the last 16.

"Now we will try and get a good result in Russia. We are going to fight."

Guardiola, who as a player was part of the only Barca team to have suffered a home defeat to Russian opposition prior to last night's loss when CSKA Moscow triumphed in the Nou Camp in the 1992-93 season, could find little to criticise his side for during the reverse against Rubin, though.

Barca fell behind inside the opening two minutes when Alexander Ryazantsev surprised everyone with a long-range piledriver, but the home side drew level through Zlatan Ibrahimovic just after half-time and had plenty of chances to add more goals only to be denied by a mixture of poor finishing, good goalkeeping by Sergei Ryzhikov and bad luck.

The hosts were then hit with a sucker-punch in the 73rd minute when Rubin broke away to net what would prove to be the winning goal through Gokdeniz Karadeniz.

Barca tried hard to get back on level terms, hitting the crossbar through Ibrahimovic and then the post deep into injury-time when Yaya Toure got his head to a Xavi corner, but the Catalan giants could not save themselves from suffering their first competitive defeat of the season.

"Football is like that," said a pragmatic Guardiola.

"With the statistics that we had, in any other sport we would have won, but not in football. I honestly think that we had a good game, but results do not always show that.

"We've had a good game, but we've lost, and you cannot do anything about that. It's disappointing because we could have taken an important step towards the last 16."

Barca midfielder Toure added: "I felt Barca had a great game, but the Russians are physically very powerful.

"We've dominated the match, but dominating isn't winning. We've had very bad luck. We had 24 shots and we've only scored one goal.

"Now we have to lift our heads and continue working. The games in Ukraine and Russia will be very difficult, but we are Barca and we always have to go out to win."