The Brazilian had an injury interrupted campaign last time around, despite the Gunners finishing second in the Premier League.
Now he is raring to go in pre-season, in contrast to a year ago when he experienced the first signs of a knee problem.
“He looks really good, he looks really sharp,” said manager Mikel Arteta to reporters last week
“He’s changed a lot of things over the summer and he’s come back in top condition again.
“When you have that baseline, other things can be built but without that foundation we don’t have a player and he needs to be in that condition to get the best out of him.
“He’s realized that and I’m really happy with what he’s shown today again. You can see by the way he looks, the way he’s moving and you can see in his eyes that there’s a spark there.”