X-rays were negative for a fracture, and he had the thumb in a splint. Gordon accompanied the club after the game to Arizona, where he will have an MRI on Thursday to determine the full extent of the injury and a timetable for his return.
"I have no idea about a timetable yet," manager Don Mattingly said.
But a dislocation is bad enough, because it means ligaments were completely or partially torn, and it is the thumb on his throwing hand. Gordon said the swelling was significant. He's virtually certain to go on the disabled list.
"I stole third and I actually don't know what was caught, but I think it went underneath the base," said Gordon, who swiped his Major League-leading 30th base. "It was a weird play and a weird thing happened. I felt I hit something real hard and got up and looked at my batting glove and it looked big. I looked at my finger and it was not a good sight."
Gordon said he had never been injured like that on a headfirst dive, but he did hurt his shoulder last year making a diving tag on defense and has tried at times this year to slide feet first but always reverts to headfirst.
Gordon had opened the game with a double to trigger a three-run first-inning rally.
Mark Ellis, in his first action since May 18, pinch-ran for Gordon.