Gabriel Martinelli returned with a bang as the Arsenal substitute's deflected effort sealed a late, long-awaited victory against Premier League champions Manchester City.Last season the Gunners pushed City in the title race, only to eventually fall just short as Pep Guardiola’s side went on to become just the second English team to win the treble.Arsenal’s inability to win a point off City last term proved costly but things are already different this time around, with Martinelli’s deflected strike securing a last-gasp 1-0 win at an elated Emirates Stadium.The substitute’s first-time effort in the 86th minute flew in off Nathan Ake, ending a run of 12 straight league losses in this fixture as they beat City in the Premier League for the first time since 2015.This match had been heading towards a drab goalless draw, with the decision not to send off Mateo Kovacic in the first half set to be the main talking point.But Arsenal dug deep and followed up their Community Shield shoot-out triumph against City by inflicting a third defeat in four matches in all competitions on Guardiola’s men.Martinelli provided a box-office conclusion to an otherwise forgettable encounter that Arsenal went into without star man Bukayo Saka.City started strongly and nearly went ahead inside five minutes.Josko Gvardiol outmuscled marker Martin Odegaard from a corner and got away a goalbound attempt that Declan Rice stopped, with Ake then blazing over after the visitors kept play alive.That let-off for the Gunners was nothing compared to the one that followed in the 17th minute.Dawdling goalkeeper David Raya received a squared pass and opened his body, taking the ball into the six-yard box.But there was an audible gasp as his hesitance allowed