The 18-year-old winger’s introduction to European football looked a breeze, with the 12 million-pound off-season signing from Southampton finishing superbly off the post after just eight minutes to give the Gunners the advantage.

The English Premier League club continued to push early at the Emirates Stadium, with Marouane Chamakh’s header drifting wide from a Mikel Arteta corner.

The provider was needed  moments later to clear Rafik Djebbour’s snap shot off the line to preserve Arsenal’s lead.

And just as Greek champions Olympiakos appeared to be building a head of steam, Andre Santos tore down the left flank and followed up his blocked cross to drill a low shot and make it 2-0.

But the double blow did not discourage the visitors, with a simple set piece from a corner enough to undo a disorganised Arsenal defence.

Ariel Ibagaza had all the time in the world to pick out the unmarked David Fuster, who powerfully headed home on 27 minutes to cut the deficit back to 2-1.

Djebbour should have levelled the scores minutes later when his driven shot was only denied by the fingertips of an impressive Wojciech Szczesny in the Arsenal goal.

With Arsenal’s back four looking anything but assured, Vassilis Torossidis and Kevin Mirallas - after robbing Bacary Sagna of possession - forced Szczesny into action once again before the interval.

The tempo of the game decreased noticeably after half-time and it was not until after the hour mark that the visitors went close again, with captain Torossidis rattling the woodwork with a 25-yard strike after cutting inside.

But Arsenal held on 2-1 to secure their first three points of the group stage.

In other Group F action, in the south of France, Marseille were impressive 3-0 winners as they dismantled a woeful Dortmund defence.

The hosts took the lead half-way through the first period after a defensive howler allowed Andre Ayew to calmly slot past the helpless Roman Weidenfeller in the Bundesliga champions’ goal.

But Didier Deschamps' men did not stop there and netted two more goals in the second half, with winger Ayew completing his brace from the spot shortly after Loic Remy doubled Marseille’s advantage.

Dortmund were first to threaten in the encounter, with Mario Gotze forcing a brilliant double save from Steve Mandanda.

But just as things were looking up for the visitors, a quick transition from the Ligue 1 outfit allowed Ayew in to score after Remy had taken advantage of a defensive slip.

Ayew almost made it 2-0 in the 36th minute but Weidenfeller was good enough in a one-on-one to block the shot.

Remy benifited from Mats Hummel’s mistake to finish in the 63rd before Ayew converted a rather soft penalty after a foul on Remy to make it 3-0.

Marseille sit top of the group after two wins in two matches while Arsenal are in second on four points.