The Brazil striker struck as the Gunners won 2-1 in LA.
Gabriel Jesus later told the club's website: “My last pre-season was not good because I was feeling my knee, so I had to have surgery and missed all of the pre-season. So, I was trying to force it during that pre-season, but at the end I couldn’t and had surgery.
“That was a little bit difficult after to come back, but this season is different. I could enjoy my holidays and then I trained a lot, and I was focused to come back well and do a good pre-season. Now I’m in different shape and can play football again.
“It’s always difficult when you concede first. We came back and won the game, so that’s the most important thing. It shows that our team tried to win in any contest. Everyone today deserved it, I think we deserved the win, and it was a good performance from the team.
“It’s a derby, it’s a difficult game, it’s a Premier League game, they have a lot of quality and it’s tough. At the end, we won, that’s the most important thing. Obviously, we are preparing for the season, so I think everyone is happy today.”