Arsenal began life without Cesc Fabregas in unconvincing fashion as Theo Walcott's goal secured a narrow 1-0 win over Udinese in their UEFA Champions League play-off round first-leg match at the Emirates Stadium.
Just a day after Fabregas completed a move to Barcelona, Arsene Wenger's team began their attempt to qualify for the group stages with a patchy display.
Although Walcott's first-half goal gave Arsenal a slender advantage to protect in the second leg in Italy on 24 August, the Gunners will have to improve to avoid an early exit.
Fabregas's ability to retain possession and launch attacks was sorely missed and Arsenal needed a large dose of luck to hold onto their lead as Udinese carved open their shaky defence several times.
"Cesc was a great player for the club but now he's gone. We dug in and gave absolutely everything tonight," Aaron Ramsey said. "The most important thing is the clean sheet. We believe we're capable of going over there to win."
Udinese captain Antonio Di Natale had described this as the biggest game in the Italian club's history, but the repercussions of failing to make the main draw would be far more damaging for Wenger and Arsenal.
In the circumstances, spending a season in the UEFA Europa League is an extremely unpalatable thought for Wenger, who was serving a touchline ban following last season's stormy Champions League exit in Barcelona.
Robin van Persie, newly installed as captain, was banned after his red card in the Nou Camp, while Jack Wilshere and Samir Nasri were also missing through injury and suspension.
Despite the lengthy list of absentees, Arsenal made a dream start as Walcott opened the scoring in the fourth minute. Bacary Sagna flicked a pass down the right wing to Ramsey and he curled over a cross towards Walcott, who had timed his run perfectly to volley past Samir Handanovic from close range.
Gervinho should have doubled Arsenal's lead moments later, but the Ivory Coast forward got in a tangle with team-mate Laurent Koscielny with the goal at his mercy.
Udinese were then handed a free-kick by some panicky Arsenal defending and nearly equalised when Di Natale's effort deceived Wojciech Szczesny and struck the crossbar.
It took a last-ditch tackle from Thomas Vermaelen to halt another incisive Udinese attack and Wenger's side lived even more dangerously when Pablo Armero surged through a gaping hole in the Gunners' defence, only to shoot straight at Szczesny.
Walcott and Gervinho continued to offer moments of menace, but Di Natale was a constant threat and the veteran striker looked set to equalise early in the second half when he ran onto Armero's pass. He was just about to pull the trigger when substitute Johan Djourou, on in place of the injured Kieran Gibbs, slid across to block his path.
When Djourou limped off soon after, Arsenal were losing possession with uncharacteristic regularity and Armero almost took advantage when the midfielder drove just over from 25 yards. Di Natale's free-kick was well saved by Szczesny in the closing stages and even when Walcott had a clear sight of goal his shot was brilliantly tipped away by Handanovic.