Arsenal were in the driving seat after Pierre-Emerick Aubameyang had scored in the first half, before Danny Welbeck headed home and Aubameyang got his second of the evening.
The home team made it four when Mesut Ozil tapped in from close range, just three minutes before Chesnakov lashed a goal back for Vorskla.
The Ukranian side kept pushing for another goal as the match entered added time, and were rewarded for their persistence.
Rebenek found himself on the left edge of the Arsenal box, and cut a ball back for Sharpar who was making a run form midfield.
Without breaking his stride, the midfielder got to the ball and leathered it in to the top left-corner of the net, with the last kick of the match.