Brentford boss Thomas Frank has no doubts about the quality of Arsenal.
The Bees host Arsenal on Sunday.
Frank said: "We are playing against a very good side.
"It was one thing to beat them a year ago.
"For me, now, after Manchester City, they are the best performing side in the Premier League.
"I said to the players today that we will need to be able to suffer and defend very well.
"If we do that then I'm convinced we will have our opportunities throughout the game. No doubt this will be our biggest challenge so far."