BALTIMORE -- Orioles starter Jason Hammel exited Tuesday's game in the fourth inning with a right knee injury, and he will see team orthopedist Dr. John Wilckens on Wednesday and -- at his request -- undergo an MRI on the area, which was operated on this season.
"By the way I was feeling and progressing, I was thinking I wasn't going to need [another surgery]," said Hammel, who missed nearly two months after undergoing arthroscopic knee surgery to remove loose cartilage, which was causing him discomfort and -- later in the season -- pain. "Tomorrow, we'll find out and see how it feels. As of right now, there's no swelling, which is a real good thing. It just puts more question marks in the back of my mind on what is going on."
Making his second start back since coming off the DL, Hammel has been the Orioles' best pitcher when healthy, and losing him for any prolonged period of time would be a serious blow to a Baltimore club trying to make its first postseason in 15 years. Acquired in an offseason trade with the Colorado Rockies, Hammel entered Tuesday's game 8-6 with a 3.46 ERA in 19 starts and was an American League All-Star Final Vote candidate.
"It feels exactly the same as it did in the game against Detroit," said Hammel, who lasted 3 2/3 innings before rookie Steve Johnson took over in the Orioles' 9-2 win over the Rays. "It was just one pitch, and then after that pitch, I couldn't load on the leg again when I tried to transfer the weight toward the plate. It's a very sharp pain in the knee in the same spot, so I really don't know what to say."
Asked if he may have thrown his last pitch in 2012, Hammel said he wasn't ready to go there yet and was hopeful it was just some scar tissue from the operation, which he was told can react with a grabbing pain like Tuesday's.
"I'm still holding on, holding on to the scar-tissue [theory]," he said. "I don't want to be done yet. If there's any way that I can pitch, I'm going to."
Hammel exited the game after throwing a ball to Rays outfielder Matt Joyce, but he said the actual injury occurred on the second pitch of Evan Longoria's at-bat, which resulted in a mound visit from catcher Matt Wieters.
"Standing there like I am right now, it didn't hurt," said Hammel, who walked Longoria. "I figured I could throw a few more pitches. As soon as I threw the next pitch after that, I knew something was wrong. I just tried to get through the at-bat."
Hammel landed awkwardly after the first pitch to Joyce, and after head athletic trainer Richie Bancells and manager Buck Showalter came out to the mound, the 30-year-old Hammel walked off the field without help. His injury comes on the heels of the Orioles losing right fielder and leadoff man Nick Markakis, who will be out at least three to four weeks after undergoing thumb surgery in Sarasota, Fla., on Tuesday morning.
"We've been down this road many times this year with a lot of different challenges," Showalter said. "The competition's enough. They've had challenges over in Tampa. Every club does. It's part of it. ... We operated a good portion of the season without Hamm and Nicky, so we're kind of experienced at it anyway. It's not the kind of experience you want to have."
Brittany Ghiroli is a reporter for MLB.com. Read her blog, Britt's Bird Watch, and follow her on Twitter @britt_ghiroli. This story was not subject to the approval of Major League Baseball or its clubs.