Brazilian defender Juan capitalised on some poor defending to fire the Italians in front and level the tie after just 10 minutes.

The Gunners grew in stature as the match went on, but could not find a way through as extra-time passed - with Roma's Max Tonetto missing a crucial sudden-death spot-kick.

Roma had started the better, and it was no surprise when they took the lead.

Arsenal failed to clear their lines, as Francesco Totti swept a low cross into the penalty area, which was completely missed by both William Gallas and Kolo Toure and went through the legs of Rodrigo Taddei.

The ball rolled all the way to Juan at the far post, and the Brazilian defender thumped his shot past Manuel Almunia.

The goal for the home side lifted the already electric atmosphere inside the Stadio Olimpico, which will host the Champions League final in May.

It also opened the match up as the Gunners - unbeaten in 17 games before this game - now had to score to progress in normal time.

After 20 minutes, Abou Diaby found himself in a good position at the far post following a corner - but could not direct the ball with enough power to test Roma keeper Doni.

At the other end, Almunia was called into action twice in quick succession.

First the Spaniard denied Marco Motta with a strong block at the near post before tipping the follow-up strike from Taddei behind at full stretch.

Arsenal were on the back foot now, as the home fans cranked up the volume in a sustained spell of pressure.

Ten minutes before the break Gael Clichy got away down the left, and floated over a cross into the area.

Diaby arrived to meet it on the penalty spot, but his header was straight at Doni.

In the final moments of the first half, Roma were screaming for a penalty when Motta charged into the right side of the Arsenal box and went down under the challenge of Clichy.

The referee, though, was unimpressed - much to the disgust of the home fans with television replays suggesting they had a strong case.

The Italians started the second half brightly and substitute Julio Baptista - who had a loan spell with Arsenal - came close to connecting with a right-wing cross as he arrived a pace in the six-yard box.

In a rare moment of action at the other end, Bacary Sagna almost squeezed a near-post header in from a corner, but Doni was well positioned.

Arsenal, though, slowly built some pressure.

Emmanuel Eboue's cross was just too far ahead of Nicklas Bendtner in the centre, with the Dane doing well to force a corner.

Roma were still a threat, though, as Totti drove the ball at Almunia with pace from 20 yards.

Diaby controlled the ball on the edge of the area following a corner, and was unfortunate to see his shot drift wide.

Wenger turned to Theo Walcott with 17 minutes left, as the England winger replaced Eboue.

In a huge let-off for the Barclays Premier League club, Baptista somehow managed to miss his kick with the goal there for the taking as the ball came across into the six-yard box.

Eduardo came on for Bendtner with five minutes left. Toure headed over from close range in the dying moments - but there was no way through as the tie went to extra-time.

There were some tired legs now, and Arsenal looked to exploit the space on the counter-attack.

After 103 minutes, Robin van Persie volleyed over after being teed up by Denilson in the six-yard box.

Walcott's angled drive, after 111 minutes, was straight at Doni.

The home crowd were screaming for a penalty when Baptista went down between Gallas and Toure, but again the referee was unmoved.

The match would, though, ultimately be decided from the spot in the lottery of a shoot-out.

Eduardo saw his opening effort saved by Doni, but Mirko Vucinic stabbed his straight at Almunia three kicks later.

Walcott, Baptista, Nasri and Denilson all scored, before Totti stepped up to send the shoot-out into sudden death at 4-4.

Toure coolly dispatched his effort, as did Sagna and then John Arne Riise for Roma.

With the tally at 6-6, Diaby slotted home before the pressure got to Tonetto as he blazed the ball over and the Gunners were into the quarter-finals.