Lopez (5-4, 4.42 ERA), who was acquired from the Orioles during the offseason and provided an early-season lift, is making his second trip to the DL. He missed more than a month with a strain closer to the elbow.
This latest injury occurred last Thursday, during a 5-4 loss to the Dodgers at Coors Field -- Lopez's only home loss, and the team's only defeat in his eight home starts. After striking out James Loney for the second out of the seventh inning, Lopez left with what was announced as a forearm strain.
Lopez underwent an MRI on Monday. Right-hander Jason Hirsh (4-7, 4.90 ERA), who is finishing his own DL stint (sprained right ankle), will be activated on Thursday night to start in Lopez's place against the Marlins.
Nice combination: Going into Tuesday night, rookie catcher Chris Iannetta had caught starter Aaron Cook's last four starts, and the right-hander had posted a 2.89 ERA -- 1.69 in the last three.
If there was a time not to start the hot-hitting Yorvit Torrealba, Tuesday was it.
Iannetta, who entered Tuesday with a .181 batting average, didn't think he had any pixie dust for Cook.
"I think that's overrated," Iannetta said. "Aaron can pitch no matter who's catching. He can do that any time when he's doing his thing, whether it's me or Torrealba. Aaron is a great pitcher who does a really good job of executing."
Torrealba posted a .391 batting average in July.
"It's hard to take Torrealba out of the lineup for any reason," Hurdle said. "But it will be a fine time to see if Chris' continued development will be enhanced through this opportunity.
"We feel he's more than a backup catcher, [but] that's the role he fits right now for our ballclub."
Iannetta caught on Opening Day and was the primary catcher in the early weeks, but Torrealba has since taken the regular catching job.
In addition, with left-hander Scott Olsen starting for the Marlins, the Rockies rested first baseman Todd Helton and started right-handed-hitting Jeff Baker.
Up next: Right-hander Josh Fogg (5-6, 4.84 ERA) will start against a former Rockie, right-hander Byung-Hyun Kim (5-5, 4.72), on Wednesday at 5:05 p.m. MT.
Thomas Harding is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.