The Bears and Redskins don't play until Week 3 this season ... but the matchup is already in Dwayne Haskins' head -- 'cause he says he's legit concerned about being hit by Khalil Mack!!!
The Washington rookie QB was out at LAX Wednesday night ... when he was asked which player in the NFL is he most worried about.
Without hesitation, the draft's No. 16 overall pick said, "Khalil Mack is somebody I would not want to be touched by!"
Bad news for Dwayne? That's probably going to happen ... and it's probably going to happen VERY early in his career.