The 22-year-old told the club's website: "It wasn't all down to me, I was in the right place at the right time. There were many blocks in there by the defenders.
"They've been outstanding since I've come into the team. Without them it could have been four or five. It is a massive result for us, we are on a good run as it is so staying in the cup will help us.
"We can build on the defensive performance that we showed and take it on from there to the game against Hull on Tuesday."
Arsenal had 26 shots during the game, 12 of which were on target.