Aaron Ramsey conceded Arsenal remain a work in progress after head coach Unai Emery collected his first win in charge with a 3-1 derby triumph against West Ham.
The hosts were forced to come from behind at Emirates Stadium after Marko Arnautovic arrowed a fine 25th-minute opener into the bottom-left corner.
Nacho Monreal found a swift response and West Ham felt Arnautovic's absence after injury robbed them of the striker with an hour played.
Debutant Issa Diop put through his own goal, but Ramsey and his team-mates could only rest easily when substitute Danny Welbeck found an assured finish deep into stoppage time.
"In the second half we created a few opportunities and it's a new process for us," Ramsey said.
"We had a tough start and are trying to improve every game. He [Emery] wants us to press high up the pitch."
The win followed losses to Manchester City and Chelsea and Wales midfielder Ramsey added: "It was difficult, it was my first 90 minutes - even [including] pre-season - so I am glad I got that in the system.
"We are progressing every game. It was open at times, but I am glad we got a win."
Ramsey returned to Arsenal's starting line-up in place of Mesut Ozil, with Goal revealing prior to the game that the German was suffering with illness and Emery moving to rubbish reports of a training ground row after a London derby date had finished.