Liverpool dump Arsenal

A contentious penalty decision allowed Steven Gerrard to put Liverpool on course with four minutes remaining, only seconds after Emmanuel Adebayor's goal looked set to send the Gunners through on away goals.

Ryan Babel made it four on the break in injury time as Arsenal attacked.

The away side's fluid midfield had initially taken the game to Liverpool and they were rewarded on 13 minutes when Abou Diaby fired inside the near post.

The faltering home team earned a lifeline after half an hour when Sami Hyypia headed home a Gerrard corner, and Fernando Torres then dipped a stunning shot into the far-post top corner in the second period to put them ahead.

Substitute Theo Walcott's thrilling run from deep to the by-line and pullback for Togo striker Adebayor could have settled the match, had Swedish referee Peter Frojdfeldt not pointed to the spot when Kolo Toure chased down another sub, Ryan Babel, at the other end moments later.

The match was frenetic from the start and Arsenal looked the more likely to open the scoring on a couple of occasions, only for Adebayor to be ruled offside.

They made the breakthrough when Cesc Fabregas found the lanky striker. His effort came back to Alexander Hleb, who laid on Diaby and the wide man finished clinically past Jose Reina.

Reina then kept out a near-post Gael Clichy cross as Adebayor lurked, denying Arsenal a two-goal cushion.

They were pegged back when Gerrard's swinging set-piece was thumped towards goal by long-serving defender Hyypia. Fabregas's goal-line lunge to head clear missed the ball by inches.

Arsenal manager Arsene Wenger was forced to bring on Gilberto Silva when Mathieu Flamini picked up a knock in an innocuous collision with Gerrard before the half.

Anfield waited to see whether penalty kicks would be the order of the day once more in Europe after their triumph last season against Chelsea.

Crouch, again making a rare start after scoring at the weekend, was unfortunate when a Dennis Bergkamp-esque flick ran just past the post. Yet his lethal strike partner Torres put paid to expectations that extra-time would be required.

As the game settled into a nervous rhythm largely devoid of chances, the Spanish hit man fed off a Crouch flick-on, turned Philippe Senderos and struck the ball into the far top corner with aplomb.

Robin van Persie and Walcott appeared as Arsenal went in search of the goal that would put them through on the away rule. Ten minutes after their introduction for Diaby and Emmanuel Eboue, Walcott led a counter-attack that left Liverpool fans with their hearts in their mouths.

Skipping past challenges from four Reds players on his way from one end of the pitch to the other, he pulled back to the waiting Adebayor - and the ball was promptly dispatched into the net to give Arsenal a sight of the semis.

However, a cruel twist snatched it away from them. Babel - recently on as a sub for Crouch - burst into the penalty area and lost balance under a minimal challenge from the chasing Toure.

In the first leg, Liverpool striker Dirk Kuyt got away with a far more obvious tug on the shirt of Hleb, yet Wenger's men were not afforded the same leniency and paid for it with their place in the competition.

Gerrard smashed the kick into the top corner and Babel made it four in the final seconds, fighting off Fabregas shoulder to shoulder before scoring inside the near post to set Anfield dreaming of another famous European triumph.