Fresh from Europa League wins, City and the Gunners meet at the Emirates Stadium on Sunday hoping they can follow up their European successes with a Premier League victory.
"Well, they're a really difficult team," the Spaniard said in his pre-match press conference. “I think Brendan and his team have done a great job. They dramatically changed the philosophy and the way of playing since they arrived and I think they had an incredible season last season.
“This season, ups and downs, like almost every team in the Premier League and some incredible results, like when they played against City.
“They can adapt and play different ways and sometimes they are really dominant, sometimes they can defend with a low block but overall they're a really, really good team."