Ralf Rangnick was watching on in the stands, and he would have been impressed with some of what he saw in the thrilling win.
Arteta would have been delighted with the start his side made and they got their reward, albeit in strange circumstances.
David De Gea went to ground as a corner was swung over after Fred stood on his foot, and was lying down facing the other way as Smith Rowe fired in from the edge of the box.
After a couple of minutes of confusion, the goal was awarded after VAR determined no Arsenal player was involved in De Gea going down.
United responded well to the setback, and equalised just before the break.
Fred made a good run into the box, and pulled it back into the path of Fernandes to guide it past Aaron Ramsdale.
Ronaldo put his side in front seven minutes into the second-half, after Marcus Rashford pulled it back into his path.
But Arsenal were level again just 90 seconds later, when Odegaard swept home Martinell’s ball into the box.
Odegaard would be involved in the fifth goal of the match too, but not in the way he would have hoped.
He brought down Fred in the box with a clumsy challenge, and after consulting the pitchside monitor, the referee pointed to the spot. Ronaldo stepped up and hammered it the down the middle to restore United’s lead.
Pierre-Emerick Aubameyang and Bukayo Saka had chances to earn Arsenal a point late on, but United did enough to hold on and go into the Rangnick era on a high.