The Chile international came on the for the final 23 minutes of Arsenal’s frustrating goalless draw with Hull City at the weekend in the FA Cup but failed to make a big impact on the game.
Sanchez has been out of action for a number of months with a hamstring injury and has only recently made his return to the first team.
However, Arsenal boss Wenger is convinced that the north London side will see the best of the 27-year-old when he lines up against his former club Barcelona on Tuesday night at Emirates Stadium.
Wenger is quoted as saying by Sky Sports: “Don’t worry about Tuesday, he’ll be tuned in. He is about focus, Sanchez.
“I don’t think he was completely ready to come on [against Hull in the FA Cup on Saturday]. It looked like that, but he grows with the game.
“He has a game based on risk and so when he’s not completely, completely highly tuned in, it becomes dangerous.”
Arsenal came from behind to beat Barcelona 2-1 when the teams last met in London in the 2010-11 round of 16, with Robin van Persie and Andrey Arshavin overturning David Villa’s first-half goal.
The Gunners are looking to reach the quarter-finals of the Champions League for the first time since 2010.
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