Arsene Wenger says he will speak with Alexis Sanchez to ensure the Arsenal forward is in the "right zone" to perform to his maximum against former club Barcelona.
The Gunners face the reigning European champions at the Emirates Stadium on Tuesday night in the first-leg of their last-16 Champions League tie.
Wenger's side are aiming to book their place in the quarter-finals of Europe's elite competition, but will have to find a way to nullify Barcelona's in-form forward three of Lionel Messi, Luis Suarez and Neymar if they are to reach that stage for the first time since 2010.
Sanchez spent three years with Barca before joining Arsenal for £35m in 2014 and has since flourished in north London, scoring 35 goals in 78 appearances.
But, while Wenger acknowledges the 27-year-old will be desperate to show his former employers what they are missing, the Arsenal boss wants Sanchez to manage his temperament in order to produce a top-level performance.
"He will be fired up, but that doesn't mean he will be in the right zone," Wenger said. "The performance zone is where you are focused and relaxed and that is what is difficult in sport.
"Sometimes when you are too focused you are not relaxed, so it's a zone where everything looks easy and sometimes when you play against your former club you are not necessarily in that zone."
Asked if he would have a chat with Sanchez to emphasise his point, Wenger replied: "A little word, yes.
"He can help us to win the game. But I know that not one player will win us the game. We need a top level team performance where everybody is spot on in the discipline and sharp physically and ready to work for the team.
"If everyone does that then maybe Alexis can make the difference but it's not especially on him. We need all our players."