Tuesday night, the Orioles lost starting pitcher Jason Hammel to a knee injury. Initially, there wasn't any real prognosis but even that news was obviously discouraging, as Hamel had already missed seven weeks this season with an injury to the same knee.

There's still no prognosis. All we know for sure is that Hammel's scheduled for an MRI on Thursday. Oh, and that he probably won't be pitching again for a while:

Hammel knows this much: His knee hurts too much to allow him to walk comfortably up a flight of stairs, let alone face stiff competition in the middle of a pennant race.

"Basically, it won't allow me to pitch. That's the way I can put it," he said. "Getting on a mound right now and trying to throw a pitch, that wouldn't work."

Although there wasn't much swelling in the knee overnight, Hammel said, "That raises more questions for me, like, what's going on?"

Also this week, the Orioles lost starting right fielder Nick Markakis to a broken thumb. In an incredibly unlikely season that now has the O's tied for first base, these latest injuries make a successful stretch run just a bit more unlikely.

Steve Johnson, who pitched well in relief of Hammel Tuesday night, probably will rejoin Baltimore's pitching rotation on Sunday, when the O's conclude a critical series in Oakland.