Arsenal's Djourou blocks a shot by Udinese's Di Natale in their Champions League first round qualifier match in London. REUTERS

Arsenal began the post-Fabregas era with a narrow victory over Udinese in the Champions League qualifier first leg at the Emirates Stadium.

Arsene Wenger's side failed to build on Theo Walcott's fourth minute goal and now face an awkward task in next week's return in Italy.

The English Premier League club, with Wenger relegated to the stands and Robin van Persie and Samir Nasri also suspended, took advantage of some disjointed Udinese defending to open the scoring early on.

Bacary Sagna released Aaron Ramsey on the right and his low cross was turned in by Walcott.

However, Arsenal couldn't capitalise against opponents playing their first competitive match of the season and it was Udinese who looked more likely to score thereafter.

Veteran captain Antonio di Natale was lively throughout and Arsenal were lucky when he hit the woodwork twice in the first half.

Udinese settled in the second half and Colombian Pablo Armero should have scored when one-on-one with goalkeeper Wojciech Szczesny but the Arsenal No.1, who was man of the match, saved well.

Walcott could have doubled Arsenal's lead late in the second half but Samir Handanovic did well to save low to his left from close range.

"The most important thing was the clean sheet," Walcott told Sky Sport.

"They are a very strong team and we will find it difficult over there but I believe, if we play the same kind of football, we can get a result."