Arsenal battled back from 0-4 down to beat top-flight rivals Reading 7-5 on Tuesday, powering their way into the League Cup quarterfinals after one of the most extraordinary matches in the competition's 52-year history.

Manager Arsene Wenger said last week that the League Cup was at the bottom of his priority list and it looked it as his second-string Arsenal team conceded four goals in the opening 37 minutes at the Madejski Stadium.

Reading, third from bottom in the Premier League, ran riot early on thanks to Jason Roberts, a Laurent Koscielny own goal, Mikele Leigertwood and Noel Hunt.

Theo Walcott gave twice former League Cup winners Arsenal hope with a goal before halftime and impressive substitute Olivier Giroud made it 4-2 on 64 minutes with a classy header. The Londoners were a different side in the second half with France striker Giroud making a big impact. Defender Koscielny made up for his earlier error with another headed goal in the 89th minute before the Arsenal fans went wild with delight when Carl Jenkinson was credited with the equaliser after he smashed the ball in after Walcott had appeared to score.

The visitors thought their comeback was complete in extra-time when the much-maligned Marouane Chamakh, making his first start since January, drilled the ball home to make it 5-4.

Pavel Pogrebnyak hauled Reading level with a header from six metres and then, just as the goalkeepers were preparing for a penalty shootout, Andrei Arshavin's shot was cleared off the line and feel kindly for Walcott to grab his second goal.

Chamakh added Arsenal's seventh just before the whistle with a smart lob over keeper Adam Federici. "You cannot play for Arsenal and give up, no matter what the score is," Wenger told ‘Sky Sports’ television. "The players understood at halftime that they couldn't come out in the second half with the same performance. Give them credit, they responded very well."

Reading manager Brian McDermott, a former Arsenal player, said conceding the first goal before halftime was the turning point. "We had to make sure we went in at 4-0 but we went in at 4-1 and I wasn't happy," he said. "I wasn't comfortable at 4-1, I don't know why, I just had that feeling.”

Elsewhere, third tier Bradford City caused an upset by beating Premier League Wigan Athletic 4-2 on penalties after a scoreless 120 minutes. Shaun Maloney and Jordi Gomez were the Wigan players who failed to convert in the shootout.

Aston Villa needed a last-gasp goal by Christian Benteke to ease past third tier Swindon Town 3-2 after having thrown away a 2-0 lead in the last 12 minutes. Benteke had opened the scoring before Gabriel Agbonlahor doubled the lead for the visitors.

Swindon substitute Miles Storey struck twice in three minutes to pull his side level only to see Benteke hammer in a cross with just seconds remaining. Southampton went down 0-3 at second tier Leeds United while Scott McDonald's goal gave second tier Middlesbrough a 1-0 win at north-east rivals Sunderland.

Barca win

Andres Iniesta celebrated being named on the shortlist for the FIFA World Player of the Year award with a glorious goal for Barcelona as the holders won 3-0 at Alaves in a King's Cup last-32 first leg on Tuesday.

The Spain playmaker had limited space on the edge of the area when he curled a delicate shot into the top corner to double Barca's lead after 50 minutes. Alaves faded, however, after Iniesta fed David Villa to slam a shot in off the crossbar just before halftime. Cesc Fabregas headed a third for the unbeaten La Liga leaders at the end.

Earlier, Valencia ran out 2-0 winners over another Segunda B side Llagostera thanks to a brace of set-piece goals on a rain-lashed artificial pitch.