The player was glad to demonstrate his versatility and help Arsenal to a 1-0 win that clinched their Champions League place.
"I've been waiting for any sort of chance to play and I've been getting a few minutes off the bench so to be able to come on in the first half was a bit of a surprise," he told Arsenal Player.
"I was aware that Mikel might have struggled a bit so mentally I prepared as if I was going to start the game. That helped me.
"To be able to come on midfield is something I really look forward to doing and it was an opportunity for me to show the boss I was capable of playing there.