Ackley, who didn't play on Sunday prior to Monday's off-day, had the thumb taped, but said it wouldn't bother him at the plate or in the field.
"It's just wrapped a little bit just for precaution, but it feels good," Ackley said prior to Tuesday's game. "I went and hit in the cage and everything felt pretty good. If it was hindering me in any way, where it would affect my performance, I think they'd have shut me down. But it felt fine."
The Mariners already have outfielders Franklin Gutierrez and Michael Morse on the 15-day disabled list, and Michael Saunders hasn't played since suffering a gash on the middle finger of his right hand by a spike while diving back on a pickoff attempt on Friday.
Saunders threw and took swings in the cage before Tuesday's game to test out the finger and said he was "definitely available" after feeling marked improvement following the Mariners' off-day.
"It's coming along nicely," Saunders said. "When I went and threw, the further I got back and really had to stay on top of it, I felt it a little bit. But it's healing nicely. I've come a long way just in the last couple days.
Manager Eric Wedge was less optimistic about Saunders, though he was excited by Ackley's quick recovery.
"Surprisingly, [Ackley] feels pretty good," Wedge said. "He felt good coming in and after taking some swings and doing some things, he's ready to go. Saunders is a little better, but still not ready. I'm hoping he'll have some availability though."
Greg Johns is a reporter for MLB.com. Follow him on Twitter @GregJohnsMLB as well as his Mariners Musings blog. This story was not subject to the approval of Major League Baseball or its clubs.