Theo Walcott, Emmanuel Adebayor and Robin van Persie were on the scoresheet as Arsene Wenger's youngsters defied their injury worries in defence to wrap up the tie 4-1 on aggregate within an hour.

The Spaniards had Sebastian Eguren dismissed, and the hosts were then able to conserve energy for their FA Cup clash against Chelsea at the weekend.

If they win at Wembley there will be genuine hope of getting something out a season where many predicted them to slip out of the traditional top four in England.

Wenger himself admits he has been amazed by how his young players have gone 18 Barclays Premier League games without defeat - and this performance will have impressed him too.

But nothing has been easy at Arsenal this season. Earlier in the campaign William Gallas was stripped of the captaincy, now Wenger is desperately short on numbers in at the back.

Ahead of this clash, Bacary Sagna was taken ill, meaning an entire back four was missing as Arsenal protected their slender away-goals advantage.

Kolo Toure held together a defence that contained Emmanuel Eboue at right-back, Kieran Gibbs at left-back and inexperienced Lucasz Fabianski in goal.

Villarreal had problems of their own, with Marcos Senna, the cornerstone of their midfield, out injured.

They did have Robert Pires stationed on the left flank, meaning it was Arsenal's past versus the club's future, as Walcott was raiding down the right.

It was a fascinating clash, with Walcott almost putting the ball out of play early on when Pires picked up a knock, only to carry on with the ball to set up an attack.

The 20-year-old showed his ruthless side again when he netted the opener in the 10th minute.

Eboue slipped the ball forward from the right, Cesc Fabregas' flick allowed Walcott to run through on goal, with the England winger chipping home high over goalkeeper Diego Lopez.

It was reward for Arsenal's bright start after Van Persie went close with a header that cleared the crossbar and a long-range effort that Lopez gathered at the second attempt.

The hosts were inches from adding a second goal after Van Persie's powerful free-kick was saved by Lopez. Adebayor's follow-up header got deflected on target but Gonzalo Rodriguez hacked off the line.

All eyes were on the assistant referee but it would have been the tightest of calls if he had flagged for a goal.

The equation for Villarreal shifted only slightly - they still needed a goal.

Diego Godin had given Wenger's side an early scare when he got on the end of Giuseppe Rossi's free-kick and forced Fabianski into a save with his scissor-kick.

The visitors then caused some nervous moments in Arsenal's defence before the break, with Rossi getting sight of goal at the near post before the hosts scrambled clear.

Pires also had a shot blocked from the edge of the area, while Godin headed over from a corner in first-half stoppage-time.

Manuel Pellegrini's men sensed that it was their time to apply pressure on Arsenal's makeshift defence. It meant all hands on deck for Wenger's makeshift back line.

Arsenal's best option was to counter attack. Van Persie was making runs from deep to cause Villarreal problems, with Godin picking up a booking for stopping one run.

No opponent got close enough to Van Persie on the hour mark and he sent through Adebayor, who took one touch before finishing past Lopez with the outside of his boot.

The third came from Van Persie's penalty and also saw Eguran dismissed.

Godin took Walcott's legs away in the penalty area but escaped a second booking for the offence. Eguran, who got a yellow card in the first half, got another caution for dissent and then disgracefully put his hands on the referee while protesting more. Van Persie kept his nerve and fired in the spot-kick.

Wenger's goalscorers were then given a breather to rest for the battles ahead.