Arsène Wenger will take what he can get at present. This narrow victory over arguably the poorest team in Arsenal's Champions League group sufficed to keep the wolves from the door for another day, although it did little to portray the club as credible contenders.

There was anxiety until the final whistle, as Arsenal surrendered a position of early strength to put their supporters through the wringer. Match tickets here ought to come with beta blockers and, on this evidence, there will surely be apprehension ahead of Sunday's north London derby at Tottenham Hotspur.

Wenger's makeshift defence, which featured Alex Song at its heart, failed to convince and Olympiakos were left to wonder what might have been had they taken some of their chances.

Arsenal, though, will play up the positives, which included the goals for Alex Oxlade-Chamberlain and André Santos, together with the form of Wojciech Szczesny, but, chiefly, took in the primacy of the result. This was a third consecutive victory, following those over Shrewsbury Town in the Carling Cup and Bolton Wanderers in the Premier League.

Wenger has always said that confidence evaporates quickly and must be rebuilt slowly. It feels painstaking at the moment. The manager's gamble, though, to use Robin van Persie and Aaron Ramsey only as late substitutes paid off and a glance at the Group F table offered reassurance. The ties against the group leaders Marseille now loom large.

Arsenal's margin for error had stood at zero and not only because Wenger had outlined his determination to take maximum points from the three home ties. Olympiakos's record in England, upon their arrival, was so dismal that it was worth printing: P9 L9, one goal scored, 29 conceded. Surely, there could be no Arsenal slip-up?

The manager said he would "suffer" from his seat in the stands, as he served the final game of his touchline suspension, yet he was up on his feet and beaming broadly when his team struck in the eighth minute. Early goals in these nervous times feel priceless and it was a moment that Oxlade-Chamberlain, on his Champions League debut, will remember forever.

The 18-year-old took a flighted pass from Alex Song and skated in from the right across the edge of the penalty area. His first touch had been assured and his determination bought him a break off the hapless Ivan Marcano. When the shooting opportunity presented itself, he remained composed enough to thread a low left-footed effort through Olof Mellberg's legs and into the bottom corner of the net.

In times gone by Arsenal's second goal might have ended the contest. It came when Tomas Rosicky released Santos and the left-back crossed for Marouane Chamakh, who could not get there. Never mind. When the ball came back to Santos, he got a break off Marcano and exposed the goalkeeper Franco Costanzo at the near post to score his first goal for the club.

But there is a brittleness about Wenger's class of 2011, an ability to make almost any opposition side look threatening. David Fuster had blown a presentable early chance and Rafik Djebbour had been denied by a sensational goal-line clearance by Mikel Arteta, which earned the Spaniard the dubious delight of a kiss from Szczesny. Djebbour put the rebound into the side netting.

Having been given ample warning, Fuster's 27th-minute goal was a shambles from Arsenal's point of view. They were caught cold by a short corner and when Ariel Ibagaza crossed, Fuster got up in yards of space to thump his header home. Chamakh had snatched at an excellent chance moments earlier, from Andrey Arshavin's chip, and Arsenal were second best for the remainder of the first-half, their defending marked by disorder and desperation. Szczesny had to be sharp and Rosicky's hack at Kevin Mirallas on the edge of the area, which earned him a booking, summed up the anxiety.

Olympiakos' defending was hardly of the bolted door variety either, and the neutral would have enjoyed the fast and open game. Arsenal, unsurprisingly, began to consider attack as the best form of defence and created opportunities in the second-half.

Chamakh frustrated for much of the evening but sent Oxlade-Chamberlain in on Costanzo with a fine pass. But the winger's second touch was poor and allowed the goalkeeper to block.

Nobody in Arsenal colours could relax, least of all the exiled Wenger, who flapped his arms. As the travelling support bounced as one, their team advanced. Vassilis Torosidis demonstrated his ability to centre menacingly and when he went for goal Arsenal hearts jumped. He cut inside and curled a wonderful left-foot shot from 25 yards that beat Szczesny but crashed against the crossbar.

Arsenal got home by the slenderest of margins.