The German has begun to make an impact after a slow start to life at the Etihad Stadium outfit, and was once more on target for Pep Guardiola's men with his goal after five minutes.
Sane showed how much he had grown as he shrugged off the attention of Hector Bellerin too easily before showing his quick feet to round David Ospina.
That represented his eighth goal from just 13 shots on target for City in all competitions, the stat underlining his opportunism and predatory instinct in making his chances count.
It was Kevin De Bruyne who put the ball over the top for Sane, taking the Belgian's assist tally to 13 in all competitions and already putting him one up on the total he managed last term.
Theo Walcott equalised for Arsenal with his fifth strike in five consecutive Premier League games against City in the 40th minute, but a matter of only 131 seconds passed before Sergio Aguero's low strike put Pep Guardiola's men back in front.