In the third inning, Liriano looked a bit stiff and awkward in delivering ball four to Matt Carpenter, and shortly thereafter manager Clint Hurdle and the team trainer visited the mound. He was lifted for reliever Stolmy Pimentel. Here's MLB.com video of the pitch in question.
At this point, the seriousness of Liriano's apparent illness isn't yet known, but this is not welcome news for a Pirates team that already has Russell Martin, Wandy Rodriguez and Jason Grilli on the DL.
This season, Liriano, including his brief outing on Saturday, has 3.97 ERA in 34 innings. Liriano was of course essential to the Pirates' playoff run in 2012, as he notched an ERA+ of 117 in 161 innings and finished ninth in the NL Cy Young balloting.