The Pirates placed left-hander Wandy Rodriguez on the 15-day disabled list Monday with right knee inflammation.
It’s unclear how or when Rodriguez injured the knee. He pitched Saturday and was scheduled to pitch Thursday.
“Wandy is not sure how he hurt his knee,” Pirates manager Clint Hurdle said. “He’d gone to the training room after his last start and complained of some right knee discomfort.”
Rodriguez was scheduled to have an MRI Monday.
“He’d felt it a couple times in his last start, didn’t think anything of it,” Hurdle said. “But I guess they extracted a large volume of fluid from his knee. … That’s all I’ve got.”
Hurdle did not name a starter to replace Rodriguez in the rotation, but said an answer is likely to come in-house.
“We’ve got a couple different guys in-house. We’ll see who lines up,” said Hurdle.
Rodriguez, who spent most of 2013 on the DL for a forearm injury, has struggled out of the gate this season.
He has allowed 26 hits, 17 runs and seven homers in 20 innings pitched over the course of four starts.
His ERA soared to 7.65 and his fastball velocity dropped a nearly 1 mph from 2013.
Jared Hughes was called up Monday to replace Rodriguez and offer bullpen help. Hughes recorded a win and three saves with Class AAA Indianapolis in six innings over five appearances.
“I was closing down there, so was good to have a little responsibility,” said Hughes. “I’m feeling good, getting ahead in the count.”
Hurdle could turn to one of his two long relievers Thursday — Jeanmar Gomez or Stolmy Pimentel — or reach down to Indianapolis.
Shortstop Jordy Mercer was not in the starting lineup again Monday night after getting spiked in the ankle Friday. The Pirates planned to push him a bit more against the Reds to gauge things.
“Closer. He took grounders again [Sunday],” said Hurdle. “Felt comfortable with a couple of innings of play, maybe a late inning if he had to. But at that part of the game I didn’t know how many more innings we were going to play. I hated to put him out there and have him on that ankle for six or seven or eight innings.”
Hurdle said Mercer can hit and run in a straight line, but lateral movements in the infield still are limited.
Grilli off grid
Hurdle said before the game that closer Jason Grilli would not be available Monday night because his pitch count over the past two days reached 27.
Tony Watson who threw 30 pitches, also was not available, but Hurdle said he was considering using Mark Melancon. Justin Wilson, Pimentel and Hughes were available from the bullpen.
Jenn Menendez: jmenendez@post-gazette and Twitter @JennMenendez.