Unai Emery will attempt to guide Arsenal towards a Europa League semi-final on Thursday by outwitting the man who wanted his job.

It was in January last year when the possibility of Arsene Wenger’s departure first began to gather pace.

Carlo Ancelotti was among the names initially discussed as a potential replacement and it is understood the Italian made it known to senior figures involved that he would be keen on taking up the challenge given his fondness for the Premier League and London.

The 59-year-old’s impressive trophy haul and experience of the continental head coach structure the Gunners were moving towards in the post-Wenger era made him an appealing option.

But as a detailed search began in earnest, Emery impressed on interview with his forensic knowledge of Arsenal’s squad and readily identifiable areas of improvement which convinced then chief executive Ivan Gazidis, now departed head of recruitment Sven Mislintat and current head of football Raul Sanllehi that the Spaniard was the right man for the job out of eight serious candidates in total.

Training and conditioning had stagnated under Wenger and while Ancelotti was viewed as a statesman in a similar mould, Emery’s hands-on coaching style addressed those urgent concerns: an energetic and demanding presence whose sheer force of will would shake the Gunners from their slumber.

Both managers have endured mixed fortunes since then. Ancelotti’s Napoli are 13 points worse off than they were under Maurizio Sarri but his iconic status in Italy has helped assuage fears they have fallen further behind perennial Serie A champions Juventus.

Emery has made positive strides in taking Arsenal on from the Wenger era but Champions League qualification is the ultimate arbiter in determining whether his maiden campaign is a success.

The Europa League has been Emery’s insurance policy in that regard, acting as a release valve for the pressure of a Premier League top-four race, offsetting domestic disappointments like the one sustained at Everton last weekend.

That insipid defeat at Goodison Park was a reminder of the alarming disparity between Arsenal’s home and away form. This remains a team still requiring goodwill in surround sound to thrive but the mere fact Emery has helped create such an environment at Emirates Stadium is testament to the progress made to date.

However, on Thursday they will be a searching examination of just how far his side have come. Napoli are by some margin the best team Arsenal have faced in the Europa League under Emery and this time they do not have the fall-back of a second leg at home. Against BATE Borisov and Rennes, the Gunners were wretched in the away leg but able to salvage the tie. A poor first leg result here would be extremely difficult to overturn next week.

Arsenal will need to employ Emery’s Europa League expertise — his three consecutive titles with Sevilla was another reason behind his appointment — and he has now been in charge of more games in this competition (Thursday is his 70th) than anyone else.

Ancelotti is not particularly accustomed to this level, with his three European successes coming in the Champions League at AC Milan (twice) and Real Madrid.

A reunion with Emery also brings back painful memories: Ancelotti was sacked by Bayern Munich the day after losing 3-0 to Emery’s Paris St-Germain side in September 2017. Nine years earlier, Wenger sounded the death knell for his Milan team, as Arsenal became the first English side to win in the San Siro and knock the holders out of the Champions League in the last 16.

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A restoration of those heady days is Emery’s ultimate aim and a return to Europe’s premier competition is the first important step.

Difficult decisions lie ahead, not least in whether to persevere with Mesut Ozil in his starting line-up. The 30-year-old had begun to earn Emery’s trust in recent weeks before a poor showing at Goodison preceded a bizarre incident in which Ozil threw his jacket in the direction of both Emery and Marco Silva as a touchline altercation ensued shortly after his substitution.

His improved form, Everton aside, is a product of responding positively to Emery’s call for greater work-rate but the temptation to use Aaron Ramsey will be high, given he continues to contribute to the cause effectively despite his impending move to Juventus.

Central midfield changes are inevitable. Matteo Guendouzi and Mohamed Elneny struggled on Merseyside and so Lucas Torreira and Granit Xhaka, assuming he is fit following a groin problem, could return while Laurent Koscielny will play if recovered from a foot injury. Xhaka and Koscielny trained on Wednesday.

Ancelotti won five of his eight matches against Wenger’s Arsenal when in charge of Chelsea and Bayern. The last of those was a 10-2 aggregate win in the 2016-17 Champions League last 16 which went a long way to confirming Wenger’s sell-by date had passed. “Each game is a different story,” Ancelotti said lon Wednesday. This is Emery’s chance to prove himself the better author.