Here are the hits and misses in Europa League matchday.
Pepe finally starts to repay Emery
It will take far more than two late goals - even two very late match-winning goals - against relative minnows such as Vitoria before Nicolas Pepe pays back his transfer fee in full, but who knows: perhaps this was the night when Arsenal's £72m forward finally started to look the real deal.
It has, it's fair to say, been an underwhelming start to life in England for the Ivorian, a struggle encapsulated by that miss at Sheffield United in a defeat that marked a new nadir in the reign of Unai Emery.
But in the interests of fairness it should also be pointed out that Pepe was Arsenal's liveliest attacker at Bramall Lane. And minnows or not, Pepe's two late free-kicks were both detonated with quality, his injury-time winner a particularly fine and classy strike. Emery's relief must have been palpable on the touchline.
Pressure for the first time since he replaced Arsene Wenger is beginning to build. True to recent form, the Arsenal boss elected to omit Mesut Ozil even on an evening when he made 10 changes to his starting line-up. But having rolled the dice on selection, Emery then had to play his last remaining get-out-of-jail cards to good effect, introducing Daniel Ceballos and Matteo Guendouzi at half-time before sending Pepe to work with 15 minutes remaining.
He'd quickly make quite the impact. But even £72m signings have to start somewhere.
Celtic dig deep for famous win
Lazio arrived in Glasgow with a game plan and up until the 67th minute, it was working a treat.
They were happy to sit back, happy to let Celtic dominate possession and happy to hit them on the counter-attack.
Celtic were sloppy in the opening hour but their luck changed when Odsonne Edouard found Ryan Christie inside the box, whose left-footed shot beat Thomas Strakosha to level things up - but more importantly change the atmosphere inside Parkhead - as the home fans started to believe again after a long period of frustration.
All of a sudden, it was a very different match, with Lazio committing men forward in an attempt to claw back control. They brought on star striker Ciro Immobile, red-hot in form, but he wasted two good chances to regain Lazio's lead.
The Italians were then punished at the death. Firstly, Christopher Jullien's towering header at the far post gave Celtic an 89th-minute lead, before Fraser Forster produced a mindblowing 95th-minute save to secure victory - and spark wild celebrations on another famous European night in Glasgow.
How Wolves are enjoying this Europa League adventure
After Willy Boly's late winner away to Besiktas, Nuno Espirito Santo's side followed it up with a come-from-behind victory over Slovan Bratislava to inflict the Slovakian side's first loss in their new stadium. It was a turnaround on the night and there's been a turnaround too in Wolves' season.
A little over a month ago 10-man Wolves were a goal down in stoppage-time away to Crystal Palace and heading for a fourth consecutive defeat. But Diogo Jota found the net in the dying moments and Wolves have not been beaten since. They are now seven games unbeaten in all competitions and looking well placed for another strong season.
It wasn't such a good night for Jota in Bratislava - he was sent off late on - but the man who set him up that day at Selhurst Park continues to shine. Adama Traore's half-time introduction was the catalyst for this comeback, shifting the momentum of the match within seconds of coming on.
There might be better players than Traore in the Premier League right now. There are not many anywhere who are more exciting to watch.
United learning art of winning ugly
Much of Manchester United's performance against Partizan flattered to deceive. Lots of passes given away, frequent fouls and there are still signs of rustiness with the three-man defensive system used by Ole Gunnar Solskjaer and from the personnel playing within it.
But the main statistic was the goals column: Partizan 0-1 Manchester United.
For all the defensive uncertainty and chances conceded, they still kept a clean sheet; and although the penalty came after a silly challenge, it was a good run from youngster Brandon Williams and the spot-kick was coolly converted by Anthony Martial on his return from injury.
United realistically don't have the players to pass teams off the park like 'noisy neighbours' Manchester City or blitz teams with attacking verve like Liverpool, but their performances so far this season show they will be involved in a lot of tight, competitive games and the tricky art of getting those results over the line is a crucial one.
Many of the young players - Williams, James Garner and Scott McTominay - will have learned a great deal from the manner they ground out victory at the FK Partizan Stadium.
Jose Mourinho was widely criticised for his drab style of play while at the club, but most fans recognise this is a season of transition for Solskjaer at United - and winning ugly is better than drawing or losing ugly
Magnificent Morelos proves his worth again
You wonder just where Rangers would be without their red-hot striker Alfredo Morelos, who came to his side's rescue again at the Estadio Dragao to claim a precious point at Porto.
The Colombian may rub opposition players and fans up the wrong way, but Rangers manager Steven Gerrard will not care one jot if his star man continues to deliver goals at his current rate.
And Morelos was at it again in northern Portugal to help earn the visitors a hard-earned draw with a well-taken goal just before half-time - cancelling out Porto's stunning opener - his 16th goal already this season moving his team up to second in the Group G standings.