Wenger has praised the Costa Rican ace, currently on-loan at Olympiakos, for his development while away from the Emirates.
"He was good and convincing going forward," Wenger said after the Champions League clash.
"He looks like he's adapted to the physical side of the European game.
"He was in Lorient, in Betis and now in Olympiakos and has learnt the toughness of the European leagues."
For breaking stories and all the great banter like us on Facebook: facebook.com/tribalfootball