Arsenal gave themselves a slender 1-0 advantage to take to Rome after a first-half penalty from Robin van Persie in tonight's Champions League clash at Emirates Stadium.
However, the misfiring Gunners should have put the tie beyond the visitors - with Nicklas Bendtner and Emmanuel Eboue both spurning golden chances as Arsenal's recent trend of poor finishing continued.
The Eternal City will host this year's Champions League final in May, and the massed ranks of visiting supporters had clearly travelled in genuine hope rather than just expectation after seeing their side qualify for the knockout stages ahead of Chelsea at the top of the group.
Arsenal had drawn blanks in each of their last three Premier League games, as manager Arsene Wenger was left to reflect on his team's inability to breakdown determined defences.
Tonight's encounter looked set to be a more open affair, with Roma all too aware of the importance an away goal would bring to the tie, and so it proved.
Arsenal midfielder Samir Nasri was handed a roaming role, and broke the offside trap to dash into the right side of the penalty area.
He pulled the ball back for Bendtner, on the penalty spot, but it was just a yard behind him and the Dane's first touch was heavy, allowing the defenders to recover and block.
Then full-back Gael Clichy picked out Nasri with a deep cross from the left - but his glancing header flew wide.
There was a warning for Arsenal when Marco Motta let fly from 25 yards with an angled drive, which was heading towards the top right corner before Manuel Almunia tipped it behind.
Roma defender Simone Loria then somehow managed to stab the ball over when he was picked out in the six-yard box by a quick free-kick.
Despite all of their possession, Arsenal were again unable to convert it into a goal.
However, the Gunners were awarded a penalty on 37 minutes when Van Persie got into the left side of the area, and was tripped by Philippe Mexes.
The Dutchman stepped up to take the spot-kick himself - and coolly dispatched his 15th goal of the season into the bottom right corner.
Van Persie was in the thick of the action again when he dashed towards the goalline and pulled the ball back, but Bendtner was crowded out at the near post.
Daniele De Rossi was somewhat fortunate to only get a yellow card following a two-footed lunge on Nasri, who went sprawling into the far touchline. The defender will, nevertheless, now miss the second leg.
The second half opened in farcical fashion as Roma kicked off when Arsenal only had nine men on the field.
William Gallas and Kolo Toure eventually dashed from out of the tunnel, with the Ivory Coast defender running straight on to the pitch - and was promptly booked by Danish referee Claus Bo Larsen for entering the field of play without permission.
Bendtner should have made it 2-0 on 53 minutes.
Eboue dashed forward and into the right side of the box, before squaring for Van Persie. The Dutchman was hustled off the ball, which broke to Bendtner on the left. The Danish international took a touch to set himself in the six-yard box - before then blazing his shot high over the bar.
Arsenal continued to press forwards, with Diaby's shot on-the-turn from 18 yards forcing Alexander Doni into a smart save, down to the keeper's left.
A mix-up in the Roma defence when Loria slipped suddenly gifted Eboue a golden chance as he latched onto a loose ball at the edge of the area, however the Ivory Coast midfielder went wide and skewed his shot the wrong side of the post, with the keeper beaten.
Wenger sent on Mexican winger Carlos Vela, replacing Bendtner, to inject some pace for the final 22 minutes.
Arsenal sat back, looking to protect their lead, but it looked a dangerous tactic.
Nasri's shot was deflected behind as Arsenal looked for a crucial second goal, but in the end had to be content with just the one to show for all their efforts.