The decision was made after Markakis had a CT scan on the thumb this morning at Johns Hopkins Hospital.
Rather than have an MRI on Monday, Markakis will fly down to Sarasota, where Dr. Brian Schofield - the same surgeon who removed the piece of broke hamate bone from his right wrist this summer - will insert a small plate in his left thumb.
Update: The Orioles just announced that Markakis' surgery will take place Tuesday in Sarasota.
Markakis is done for the regular season, but the Orioles remain optimistic that he could be available if they get deep into the playoffs. This procedure could speed up the healing process and accelerate the timetable for his return to the active roster.
"He's going to fly out to Sarasota in the morning," said manager Buck Showalter. "They've already looked at the CT scan and the X-rays and I think if things proceed like we expect them to, they'll probably do a surgery tomorrow afternoon if they can get it scheduled. It's kind of good news, because they think by actually putting a little plate in there - it's kind of called a T plate - it should speed up the recovery time.
"We've got Nick on a flight in the morning and the doc's going to look at him down in Sarasota. He's already seen the X-rays and CT scan. All he has to do is verify the findings, and if that's the case, then they can get him in and do the surgery tomorrow afternoon in Sarasota. It could speed up the process by getting this plate in there."
Asked if he's cautiously optimistic, Showalter replied, "Cautiously, and I'm optimistic. But it's a pretty ugly thumb today. Black and blue and swollen. He knows there's some looseness there that they need to bring it all together. They think it could potentially speed the healing process. September is not an option, so we've got to hopefully play good baseball and make October an option."
Showalter indicated last night that surgery would rule out Markakis for the postseason.
"The way that they were presenting it to me last night, and now with this, it's another lesson for me to stay out of the medical business," he said. "I listenened to them and Nick on the bench today because they finally got everything together. They've been working very hard with this. It's not easy to schedule this type of stuff. Anybody here that's had anything done medically, we're very fortunate to be able to get this done, hopefully. So, I was wrong.
"I know Nick likes the people here and really has a good repoire and confidence level down there. It's the third surgery. He had them all in the same year. I hope we got them all out of the way."