After winning 2-0 at Athletic Bilbao in their Champions League opener, Arsenal dispatched the Greek champions at the Emirates Stadium to maintain their 100 percent record in the league phase.

Martinelli netted in the first half and Bukayo Saka wrapped up the points in the closing moments.

The north Londoners weren't at their best but still managed to grind out a seventh win from nine games in all competitions this season.

Mikel Arteta's men improved their impressive home record in the Champions League with a 10th clean sheet in their last 13 matches in the competition.

The Gunners are back in action on Saturday against West Ham as they aim to close the two-point gap on Premier League leaders Liverpool.

Olympiacos' visit was a welcome trip down memory lane for Arteta, who was up against one of his childhood coaches in Jose Luis Mendilibar.

Aged 14, Arteta was in the Athletic Bilbao youth system where Mendilibar, now in charge of Olympiacos, was his coach.

Arteta still cites the lessons learned from his football education in Spain as pillars of his philosophy at Arsenal and the pupil put that wisdom to good use against his mentor.

England trio Saka, Declan Rice and Eberechi Eze were all dropped to the bench by Arteta as Martin Odegaard returned to the starting line-up after a shoulder injury.

- Sublime Odegaard -

Arteta's squad rotation produced the desired effect and Arsenal should have taken the lead inside 90 seconds.

Myles Lewis-Skelly ran unchallenged towards the Olympiacos penalty area and across to the unmarked Martinelli, who headed wide from six yards.

Martinelli made amends for his miss in the 12th minute.

Odegaard unfurled a pin-point pass that sliced through the Olympiacos defence towards Viktor Gyokeres.

Gyokeres shrugged off his marker and smashed a fierce strike that cannoned back off the post to Martinelli, who slotted home from close range.

Odegaard had come off the bench to inspire the comeback for a 2-1 win at Newcastle on Sunday and the sublime ball that started the move underlined the Norway midfielder's importance to the Gunners.

Martinelli's third goal this season was no more than Arsenal deserved for a vibrant start but they were fortunate to remain ahead moments later.

Former Wolves winger Daniel Podence eluded the Arsenal rearguard for a volley that forced a superb save from David Raya.

Odegaard teed up Gyokeres for another dangerous raid but the striker's shot whistled over.

Picked out by Odegaard, Leandro Trossard had a chance to double the lead after the interval, but the Arsenal forward's attempt to loft his shot over Konstantinos Tzolakis from close range was repelled by the Olympiacos keeper.

Although Olympiakos had scored just once in their previous six Champions League matches, they carried a threat in patches and were only denied an equaliser by a tight offside decision that ruled out Chiquinho's finish.

Tzolakis made a brilliant double save to stop Odegaard before Saka came off the bench to put a flattering gloss on the scoreline in stoppage time.

Odegaard found Saka for a shot that was powerful but should have been dealt with Tzolakis, who allowed it to squirm through his legs into the net.