After a goalless first 45 minutes, Granit Xhaka broke the deadlock shortly after the break with a sumptuous free-kick.
Emery's side are now up to nine points in the league, level on points with north London rivals, Tottenham.
It was another tough 90 minutes to endure for Spanish manager Benitez, whose side remain in the bottom three with a single point, equalling their lowest tally after five games of a Premier League season. At Newcastle, Torreira was the difference and he galvinised the Arsenal team to victory.
"I think Manchester United and Chelsea will both battle it out to sign him if they feel he is seriously considering leaving Arsenal". We are happy to win today'.
Unai Emery is persisting with introducing Lucas Torreira to the Arsenal team, and yet again he was on the bench and was brought on for the second half, and although we have all been impressed with Matteo Guendouzi since the start of the season, it is obvious that he will be a backup for Torreira when he is ready to start every game.
"The result gives us confidence but the things on the pitch, individually and collectively, that we can improve", he said, per Sky Sports. We try it a lot in training and I was happy to score'.
Pierre-Emerick Aubameyang failed to test Dubravka from seven yards out after Lacazette played him into space on the left, while Lucas Torreira skied a first-time effort from 19 yards out after being teed up by Ozil on 71 minutes.
How to read this, a third successive victory for Arsenal - their second away from home - by September was best done through context.