Exactly how this became a successful evening for Arsenal will remain a mystery but Freddie Ljungberg may consider that, at this point in his young managerial career, there is no need to apologise for a stroke of good fortune.

Two goals in three minutes late in the second half, the excellent Bukayo Saka setting up the first for Alexandre Lacazette and then scoring a classy equaliser, pegged back Standard Liège and rescued a scrappy display but the most important turning point came elsewhere. Had Vitória Guimarães not contrived an improbable late turnaround at Eintracht Frankfurt, Ljungberg’s side would have finished second in Group F and be confronted with the possibility of facing, among others, Internazionale or Ajax in the last 32. Instead they are group winners and will face a softer set of options, although their performances will need to improve markedly if further complications are not to arise.

At least they never looked remotely like falling to the five-goal defeat that would have ended their interest in the competition. Not even this side is capable of a capitulation that dramatic although there was a brief spell in the second half when Standard Liège, ahead through two deflected goals and threatening more, could have made the final stages distinctly awkward.

Instead Saka, who Ljungberg said had initially been “a bit upset” at his selection in a relatively unfamiliar wing-back role, rose up out of the blue and shifted the entire evening’s tone.

“He was amazing,” Ljungberg said of Saka, with whom he has had a close affinity since coaching the 18‑year‑old in the club’s under-23s. “He’s a tremendous talent and you could see it again. His final ball is always effective and there’s always an end product to his work.”

The devilish left-sided delivery he produced for Lacazette in the 78th minute, presenting a chance the stand-in captain could hardly miss, was fine evidence of that. It was Arsenal’s first moment of real threat in what had been a turgid second-half showing and he quickly bettered it. The second goal, curled in delicately with his right foot after a one-two with the substitute Gabriel Martinelli, was a hugely impressive piece of initiative and vindicated an experimental selection that Ljungberg half-filled with fringe players.

Quick Guide Roundup: Djokovic serves up defeat for Celtic Show Cluj booked their place in the knockout stages by defeating a makeshift Celtic side in Romania. Second-half goals from defender Andrei Burca and midfielder Damjan Djokovic inflicted Celtic's first Group E defeat. Neil Lennon's side had already secured top spot in the group, so the manager made a number of changes, with 18-year-old Scott Robertson starting in midfield, and 16-year-old Karamoko Dembélé comimg on as a late substitute. "Obviously I'm disappointed to lose the game but [I'm] very pleased with what I got out of the game," Lennon said. "Scott Robertson made his debut and had a terrific debut. For such a young player he showed such maturity and composure." Mönchengladbach are top of the Bundesliga but their European campaign is over after defeat to Istanbul Basaksehir. Enzo Crivelli's last-gasp winner sent the Turkish side through, with Roma also sneaking through after a 2-2 draw with Wolfsberger. In Group C, Getafe won their eliminator against Krasnodar 3-0, with all three goals coming in the last 15 minutes. Basel topped the group after a 2-0 win over Trabzonspor. In another decisive contest, Ludogorets edged through from Group H after drawing 1-1 with Ferencvaros In Group A, Apoel surprised Sevilla, winning 1-0 in a game between two teams who had already qualified. In Group D, LASK Linz grabbed top spot from Sporting with an emphatic 3-0 win, while PSV and Rosenborg drew 1-1. In Group G, there were five goals in the first 33 minutes, and none after, as Porto beat Feyenoord 3-2 to top the group. Malmö got the win they needed in a cross-border derby at Copenhagen, who still crept through after Dynamo Kyiv were held at home by Lugano. Elswhere, two goals from Joris Gnagnon earned Rennes victory over Lazio, ending the Italians' faint hopes of progress. Photograph: Inquam Photos/X03608

“I feel sorry for our young players because a lot of them haven’t been out on loan, so they don’t have exposure to 90 minutes of men’s football for periods,” Ljungberg said in reference to individuals such as Saka, Reiss Nelson, Emile Smith Rowe and Konstantinos Mavropanos, all of whom started.

“In this game I wanted to get them on the pitch to get that experience because I know how good they are. Some of them made some mistakes today but they will learn from that and won’t redo them.”

Standard Liege vs Arsenal FC

epa08066322 Players of Liege celebrate their 1-0 lead during the UEFA Europa League group F soccer match between Standard Liege and Arsenal FC at Stade Maurice Dufrasne in Liege, Belgium, 12 December 2019. EPA/STEPHANIE LECOCQ Photograph: Stéphanie Lecocq/EPA

Saka had been Arsenal’s main threat in a first half that they shaded in difficult conditions, an icy wind blowing through the stadium’s two open corners and a rutted pitch making slick passing football almost impossible. Standard were backed by a hostile crowd and would, as it turned out, have qualified with a win owing to Vitória’s victorious exploits in Frankfurt. But they had to thank their goalkeeper, Arnaud Bodart, for twice repelling angled efforts from Saka and he also diverted a Smith Rowe shot, executed after a characteristically smooth swerve of the hips from the winger, wide with an outstretched toe. When the hosts did threaten, it generally arose from sloppy work from Arsenal, such as the concession from Mavropanos inside his own area that allowed Mehdi Carcela a half-chance.

That had nothing on the issues that dogged Arsenal after the restart. Standard came out strongly and scored with their first attack of the second half when Samuel Bastien was allowed to advance and shoot from 22 yards. The ball ricocheted off Sokratis Papastathopoulos and spun agonisingly beyond Emiliano Martínez, who had already committed in the opposite direction.

It was one-way traffic by the time Selim Amallah, inexplicably handed possession by Joe Willock, shimmied this way and that before unloading a strike that snicked off Mavropanos and nestled in the bottom corner. Arsenal’s capacity for implosion hardly needs outlining nowadays and at that point the worst, albeit unlikely, could not be ruled out. But their ability to confound is equally great and, just as they had consigned a generally dire performance to memory against West Ham with three quickfire goals three nights previously, they hauled themselves out of the fire with two more back-to-back moments of brilliance.

“They go and they go, and they go, and they don’t stop,” Ljungberg said of his team. “It’s tremendous. I’m really proud of them.” His band of youngsters are, like him, learning on the job; the relief this time was that, in the end, the lessons to take from the Belgian winter were not particularly harsh.