BALTIMORE — Brett Gardner’s left thumb will undergo an MRI exam on Friday to make sure the X-ray taken Wednesday didn’t miss an injury. The X-ray was negative.

“He is better today,’’ Girardi said of the left fielder who left Tuesday night’s game with discomfort in the thumb after a check swing.

It’s the same thumb Gardner had surgery on last year and missed 40 games. Gardner didn’t start Wednesday and wasn’t in the lineup Thursday.

“(Trainer) Geno (Monahan) was encouraged by (the X-ray),” Girardi said. “Maybe we will have him this weekend. The MRI is just to make sure we are seeing what we are supposed to see.’’