Nicolas Pepe finally showed why Arsenal made him the club's record signing in the summer with a brilliant, two-goal late show to rescue the Gunners in the 2019/20 UEFA Europa League on Thursday night.
Pepe found the net from a pair of expert free-kicks to seal a 3-2 win at home to Vitoria Guimaraes in Group F. Arsenal had been labouring before Pepe came off the bench in the 75th minute, with young players such as Joe Willock looking out of their depth.
The 20-year-old was hooked at the break for a second match in a row. Willock already appears shorn of confidence, with head coach Unai Emery regularly shunting him out of position.
By contrast, Manchester United saw young players seize the chance to impress away to Partizan Belgrade. In particular, left-back Brandon Williams caught the eye by winning the penalty Anthony Martial converted to earn a narrow win in the Serbian capital.
Martial is working his way back to full fitness after a hamstring problem, and the Frenchman already looks like an upgrade over United's other options at centre-forward.
It's a different story for Luke Shaw and Ashley Young, neither of whom appear to be a better option at left-back than burgeoning talent Williams.
Winner: Nicolas Pepe
Of all the questionable decisions Emery made during Monday night's 1-0 defeat away to Sheffield United, withdrawing Pepe on 78 minutes was the most dubious. Pepe was Arsenal's best player during a tepid performance, with his quickness and desire in sharp contrast to the pedestrian pace of play.
The winger wanted the ball but was taken off just as he was visibly growing in confidence. Fortunately for Emery, Pepe carried the same confidence into European action and ultimately spared his manager's blushes.
Arsenal were out-thought and out-fought for 80 minutes by a Guimaraes side rugged in midfield, organised in defence and rapid on the break. With no coherent style of play, the Gunners needed individual inspiration to bail them out, and Pepe duly provided it:
The sweet finish showcased the wand of a left foot and flawless technique Pepe used to torment Ligue 1 defences for Lille last season. Both of those attributes came to the fore again when Pepe brought Arsenal all the way back from 2-1 down in stoppage time.
Moments like these are why certain players can justify price tags worth £72 million. Teams pay fees in that rarified bracket to acquire players talented enough to help them win even on off nights.
Emery's system is heavily reliant on isolated examples of magic. Most of them come from striker Pierre-Emerick Aubameyang, but Pepe is beginning to look like another star capable of dragging the Gunners over the line.
Loser: Joe Willock
Everything appeared set up for this to be Joe Willock's breakout campaign. Aaron Ramsey leaving for Juventus left Arsenal needing a midfielder to pick up the goal-scoring slack from the middle.
Willock has the core skills to find the net regularly. He's also had ample opportunities for playing time with Mesut Ozil continuing to be frozen out by Emery, while Lucas Torreira is no longer a regular member of the starting XI.
However, Willock is yet to make the grade as an academy graduate capable of becoming a fixture in the first team. He struggled to exert himself against Guimaraes after labouring against the Blades.
Another substitution at the break was hardly a surprise, but it did serve to emphasise how Willock's development is beginning to stall. His case hasn't been helped by Emery shuffling him into different positions.
Willock isn't a natural No. 10, nor is he an enforcer or a deep-lying playmaker. Instead, the youngster is at his best when playing a box-to-box role, able to break from the middle and support the attack with late runs.
Willock's progress will remain stuck in neutral until he is used properly.
Winner: Anthony Martial
Injuries and inconsistency have blighted Martial's United career since he moved to Old Trafford in 2015. Yet the Frenchman's talent has never been in question.
Martial delivers when he's fully fit, something he did when he stepped up from 12 yards two minutes before the break in Belgrade. Calmly rolling in the penalty showed the coolness and assurance as a finisher that come natural to the former AS Monaco ace.
The Frenchman is Ole Gunnar Solskjaer's best choice for centre-forward because he'll put away more chances than Marcus Rashford. Martial will also play with greater strength than 18-year-old Mason Greenwood.
Scoring goals consistently has been United's main issue to start the season. It will be solved quickly if Martial can stay off the treatment table.
Loser: Ashley Young and Luke Shaw
The full-back berths have been a weakness for United longer than issues up front have persisted. United spent £50 million in the summer so Aaron Wan-Bissaka could be the answer at right-back.
It might be significantly cheaper to fix things on the left side of defence thanks to the emergence of Brandon Williams. Still just 19, Williams already looks strong enough in both phases of the game to learn on the job as the Red Devils' left-back of choice.
Williams was relentless in the way he raided forward against Partizan. He always gave the man in possession an option on the overlap.
Those sprints into the final third finally paid dividends when Williams won the penalty Martial tucked away.
It was equally important for Williams to show the recovery pace and discipline to be an asset in defensive areas. He consistently got back into position out of possession and helped United's 3-4-1-2 shape become a 5-4-1 formation without the ball.
Ultimately, Williams had produced a complete display:
His efforts weren't lost on Solskjaer, who praised Williams' "fantastic attitude, great defending, great in the air, brave… he gets us the penalty by his driving forward with the ball so we’ve found a left-back there!" per Andy Hall of AS.
Solskjaer's last words should have Shaw and Young worried. The former has never been able to avoid injury, while the latter is not a natural at the position, and at 34, his skills are deteriorating.
United are showing a greater willingness than in recent seasons to give young players a chance on Solskjaer's watch. It means there shouldn't be any way back for Shaw and Young as long as Williams continues to impress.