Nicolas Pepe scored Arsenal's second goal. The hope is that he can kick on from there. Pierre-Emerick Aubameyang provided the assist for that one and scored the third himself. As for Mesut Ozil, he set up both of those goals with driving runs from deep.
But for all the big names, the big signings and the even bigger salaries among this Arsenal team, it was the performance of teenager Gabriel Martinelli that stood out. He also showed a lot of the qualities that have been missing during the club's dismal run of form.
Martinelli's equaliser, on his full Premier League debut, turned the game around. Arsenal had been dreadful up until that point, weighed down by the pressure that has been building throughout a run of nine games without a win - the club's worst in 42 years.
The 18-year-old Brazilian was the exception. It wasn't just the finish, a measured strike into the corner of the net. It was already apparent in his previous appearances that he was capable of that - netting seven times in six starts for the Gunners in the cup competitions.
Martinelli's seven Arsenal starts in all competitions
Sep 24 – Nottingham Forest (h) – Two goals
Oct 3 – Standard Liege (h) – Two goals
Oct 24 – Vitoria Guimaraes (h) – One goal
Oct 30 – Liverpool (a) – Two goals
Nov 6 – Vitoria Guimaraes (a) – No goal
Nov 28 – Eintracht Frankfurt (h) – No goal
Dec 9 – West Ham (a) – One goal
The really striking aspect was the obvious enthusiasm in his play and the contrast in this respect between him and his team-mates. "Martinelli is enjoying himself out there," said former Arsenal striker Alan Smith on co-commentary for Sky Sports.
Not everyone gave off that same vibe.
Interim head coach Freddie Ljungberg deserves credit for identifying the qualities that the youngster would bring to the team. He referred to most of them in his pre-match interview.
"We want to get the energy into the team and shake things up a bit," he told Sky Sports. "He has done very well in Europa League games, looks dangerous, scores goals and works hard. He runs in behind, he's really quick, and I think he will do well."
That hard work, in particular, was the difference. No Arsenal player regained possession of the ball more times than Martinelli. No Arsenal player made more tackles. No Arsenal player made more blocks. In particular, it was the intensity of his sprinting that set him apart.
Martinelli made 20 high-intensity sprints in the game. That was far more than anyone else. Twice as many as any other Arsenal player. He was still making them in the seventh minute of stoppage time, darting in behind the back line to latch onto Ozil's probing pass.
Arsenal's problems are unlikely to go away after consigning West Ham to their seventh defeat in nine games. There were too many worrying signs in the first hour at the London Stadium on Monday evening to make that claim with any great confidence.
But Martinelli's inclusion is a step in the right direction.
Ljungberg will surely stick with him now.
This was the night he became the youngest Arsenal player to score on his first Premier League start and the fourth-youngest scorer for the club in the competition full stop. But regardless of his age, Martinelli showed his more experienced team-mates the way out of this rut.
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Ljungberg had been reluctant to turn to youth against Brighton.
"I felt I want to play the experienced players when it's such a difficult situation like it is at the moment," he explained. "I decided not to pick all the young players that are going to change the future of this club. I made a conscious choice to put down the older players to take the responsibility and change the games."
Martinelli has now shown there is another way.
This young forward has quality, of course, but plenty at Arsenal have that. It is his desire that his team-mates must replicate. If that happens, perhaps Arsenal still have a chance of turning their season around.