The right-hander was scratched from his scheduled start against Toronto on Thursday after experiencing back spasms Wednesday.
Trainers treated him with muscle relaxants and a massage. On Thursday, he reported no pain after throwing for five minutes from 75 feet.
Before the A's faced the Orioles on Friday, Gray said, ''Thankfully it's really kind of progressing better and better. I threw, and it really couldn't have went any better.''
Gray is 12-4 with a 2.06 ERA.
Oakland manager Bob Melvin said Gray will throw a bullpen session Saturday, and has ruled out the possibility of the disabled list.
Melvin says, ''If everything feels good, then we'll pick a date for him. The earliest would be Monday.''