Arsenal secured a phenomenal 3-0 victory in Istanbul on Wednesday night, making extremely light work of Fenerbahce.
Much of the pre-match focus was on the Gunners' depleted options, but Arsene Wenger fielded a strong XI that eased to a win.
Kieran Gibbs opened the scoring with a far-post finish, then Aaron Ramsey fired in from distance to double the lead. Olivier Giroud converted a penalty late on to effectively seal it, and the return leg would seem just a formality now.
It's never too soon for a crisis at Arsenal football club, and Wenger's men knew a loss here could spell serious danger for the season ahead.
The visitors started with one solid minute of possession, attempting to quieten the crowd and take the sting and hunger out of the home side's approach.
It was a pattern that emerged several times in the game, and with each passing compilation the away side created, vicious boos and whistles would accompany.
Santi Cazorla played off the left-hand side but frequently cut in, and he attempted a slide-rule pass between the centre-back and left-full-back. The intention was to slip Theo Walcott in off the edge, and 'keeper Volkan Demirel was called into action three times early on.
The Turk showed fantastic awareness and ability to judge when to come out, nicking the ball off the winger's toe each and every time.
Olivier Giroud tried his luck next but to no avail, and at the 25-minute mark, Fener had barely touched the ball, yet Arsenal were missing the vital goal.
Aaron Ramsey's frustrations got the better of him as he dragged a shot rather wide from distance, and soon after the first real blow of the evening landed.
Pierre Webo's high foot caught Laurent Koscielny square in the face, the striker received a yellow card and the defender was subbed off, blood pouring from his forehead.
A flurry of chances fell Arsenal's way just before the break, but desperate defending from Fener prevented any late goal.
The second half started with a bang: Ersun Yanal clearly said something at halftime as Fenerbahce tore out of the blocks, but the Gunners delivered a sucker-punch goal just four minutes later.
Ramsey showed incredible patience and composure to wait for exactly the right moment to slot Walcott in, and the England international rolled it across goal to find Kieran Gibbs at the back post.
An easy finish, and first blood to the visitors.
The Gunners followed up with more possession, and after Walcott missed a good chance to make it two—thanks to great work from Volkan again—Ramsey obliged.
Steaming forward from a central midfield position, the Welshman, unchallenged, steadied himself and fired home from 22 yards.
The home fans, perplexed, were verging on silent at this point, and it took a Moussa Sow effort from way out to get them on their feet once again.
But when Walcott tore through down the right and drew a penalty which Giroud expertly converted, every person inside the Sukru Saracoglu Stadium knew it was over.
Even Nacho Monreal made it onto the pitch for a precious 10 minutes, giving Wenger additional options in defence ahead of this weekend's Premier League action.
Key Player Grades
Aaron Ramsey: A
Ramsey played one of his best games in an Arsenal shirt to date in Turkey, running the show from midfield. He was heavily involved in the Gunners' critical first, then steamed forward to bury the second in the bottom corner. Class performance.
Jack Wilshere: B+
Survived a knock on the ankle early on to play very well, recycling possession easily and looking dangerous going forward.
His burst into the box to force a save from Volkan was superb.
Dirk Kuyt: C-
Kuyt's poor performance epitomised Fener's limp display, and he, along with every other forward on the home team, lacked any real threat.
The Dutchman recorded one shot of note from outside the box.
Full Player Grades
The Gunners travel to Craven Cottage for Saturday's early Premier League kick-off, hoping for a win to put their (domestic) season on track.
Fenerbahce face Eskişehirspor at home on Sunday.