MADRID, Jan 26 (Reuters) - Barcelona's 18-match winning run ended in stunning fashion on Thursday when Real Zaragoza exposed their defence with a devastating display of high-class finishing on their way to a 4-2 victory in the King's Cup.
Zaragoza hit the visitors with a three-goal salvo in the space of five first-half minutes to take a commanding lead in their quarter-final first leg before the half hour was up.
Argentine forward Diego Milito grabbed the first in the 22nd minute and Brazilian strike partner Ewerthon fired in two more before Barca had time to recover.
A Henrik Larsson header and a controversial penalty from Ronaldinho put Barca back in the game but, just when the Catalans looked as though they might escape with a narrow defeat, Milito completed his double with an injury-time penalty for Zaragoza.
Barca had gone 24 matches since their only previous defeat this season, which was a 2-1 loss to Atletico Madrid on Sept. 18.
Real Madrid and Espanyol have already booked their places in the semis of the Cup, but the tie between Valencia and Deportivo Coruna has yet to be completed.
The second leg at the Mestalla was abandoned a minute before halftime after the linesman was hit on the head by an object thrown from the crowd with the aggregate score at 1-1.
The Spanish Football Federation has decided that the remaining 46 minutes will be played behind closed doors.
There was little indication of the surprise in store for the Catalans as they enjoyed the best of the early possession and had several chances to take the lead in the opening minutes.
Just as Barca looked as though they might gain the upper hand, Zaragoza stunned the visitors.
Milito delivered the first blow when he darted out from between the Barca back four to meet a fine through ball from midfielder Cani and drilled a shot under reserve keeper Albert Jorquera.
Two minutes later, strike partner Ewerthon hit them with a second. The Brazilian picked up the ball on the right of the area, cut inside fullback Oleguer and although Jorquera got his hands to his fierce shot the ball ballooned its way into the net.
Barca were still reeling when the former Borussia Dortmund player swept the ball past the helpless keeper after beating the offside trap to race on to a lofted pass from midfield.
Zaragoza's first-half performance was reminiscent of Chelsea when they exposed the Primera Liga side's defence by scoring three quick-fire goals in the first 20 minutes of their 4-2 victory in the first knockout round of the Champions League last March.
The punch-drunk visitors eventually got back into the game when Sweden striker Larsson powered in a header after a fine cross from Giovanni van Bronckhorst seven minutes from halftime.
They were given another break when Ronaldinho smashed home a controversial penalty awarded when Argentine forward Lionel Messi went to ground in the area on the hour.
But Zaragoza restored their two-goal advantage ahead of next week's second leg when Milito fired home a penalty after Barca defender Edmilson had handled in the area.