The Barca juggernaut was, if not derailed, at least given a good bump by Zaragoza, who netted three times in four first-half minutes to establish a 3-0 lead.

Diego Milito and Ewerthon, with a brace, had left the visitors seemingly dead before Henrik Larsson and Ronaldinho closed the gap with strikes after 38 minutes and on the hour.

However, in injury time of a pulsating encounter, Milito struck again to give Frank Rijkaard's men work to do in the return at the Nou Camp on February 1.

The defeat put an end to Barca's winning run which stretched back 130 days and took in 13 league wins, three in the Champions League and two in the Spanish Cup.

There was defeat for Serie A leaders Juventus too, who went down 3-2 at home to Roma in the first leg of their Italian Cup quarterfinal.

Roma took the lead against the run of play at a snowy Delle Alpi stadium in the 38th minute. Olivier Dacourt picked out Mancini whose intelligent run sprung Juve's offside trap, and the speedy South American cut inside Gianluca Pessotto before firing a right-footed shot past Christian Abbiati.

Roma went further ahead in the 61st minute when Tommasi, captain for the day in the absence of the injured Francesco Totti, raced on to Mancini's clever pass before clipping the ball past the advancing Abbiati.

Perrotta made it 3-0 with a cool finish six minutes later after good work from substitute Aleandro Rosi.

But Juventus staged a rousing fightback led by substitute Alessandro Del Piero whose two goals mean Juventus are still very much in the tie.

Del Piero struck from close range after Pavel Nedved's cross had caused panic in the Roma defence to lift the home side's spirits.

And Juve's leading scorer doubled his haul in stoppage time when his heavily deflected free-kick found a way past Gianluca Curci.