How do you stop Luis Suarez and Daniel Sturridge?
It's a question that has foxed most managers this season but Arsène Wenger provided the answer in November when Arsenal became the only side to prevent either of Liverpool's front two from scoring when they start together in the Premier League.
Suarez and Sturridge are perhaps even more deadly on home soil but Wenger believes his team can keep them quiet again at Anfield on Saturday - if they starve them of service.
At Liverpool the task might be a bit more difficult but the philosophy on our side has to be the same - to master the ball and to have the ball and to dominate the game
"[The key is] for us to dominate the game and leave them as few balls as possible," said Wenger. "That will be one of our targets of course.
"At Liverpool the task might be a bit more difficult but the philosophy on our side has to be the same - to master the ball and to have the ball and to dominate the game.
"Liverpool have a strong offensive force with Sturridge, with Suarez, with Coutinho, with Sterling behind. All these players can score goals and make a difference. So what you want on our side is a strong defensive performance."
Arsenal were linked with Suarez last summer but Wenger insists any new striker would have been a supplement to Olivier Giroud and not a replacement.
"No [I have no regrets]," said the manager. "You sometimes have regrets when a player played for you, and scores goals or does well somewhere else.
He was never our player, it is just a situation that did not come off and that is it.
"But it was not to replace Olivier Giroud. We never wanted to replace Giroud, we always had complete confidence in him. I said at the beginning of the season that he always does better in the second year everywhere and he shows that again this season.
"He is a very important player for us and I am not surprised at all he is doing well."