Eibner went to the ground in a heap, and as his teammates huddled around, he was eventually carted off the field with what the team called a left lateral sprain of his left ankle.
Eibner actually feared the worst -- a broken bone or an Achilles injury. But an MRI on Wednesday revealed it was just a sprain. Still, Eibner had to be placed on the 15-day disabled list and outfielder Rey Fuentes was recalled from Triple-A Omaha.
Also, the Royals optioned right-hander Dillon Gee to Omaha and recalled right-hander Peter Moylan.
Eibner was relieved with the MRI news.
"Yeah, great news," Eibner said. "Nothing broken and nothing wrong with the Achilles. Big news. Just a sprain. We'll wait 5-7 days and see how it is then."
The injury, though, had unfortunate timing: Eibner made his Major League debut over the weekend and was 6-for-13 (.462) with three doubles since.
"It's tough," Eibner said. "But I've been through it [injuries] in the Minors so I'm prepared to do what I need to do to get to work."
Eibner also was moved by the support from teammates: The starters in Tuesday's game all stood around him near the warning track as he was being examined after the injury.
"That's the kind of clubhouse this is," Eibner said. "Everyone cares about each other."
Manager Ned Yost said Moylan was recalled just so the Royals have an extra arm in the bullpen. With Chris Young replacing Gee in the rotation on Sunday, the Royals were short a man in the bullpen.
"We were stuck knowing that Eibner would go on the DL: Do we need another position player or do we need another arm?" Yost said. "Well, we needed both."
Fuentes started the season with the Royals and hit .238 with three RBIs in six games. He was hitting .302 with two doubles and six stolen bases for Omaha.
Moylan was optioned last Sunday, but was allowed to be recalled due to the injury to Eibner. Moylan had been 2-0 with a 2.45 ERA with the Royals.
Jeffrey Flanagan has covered the Royals since 1991, and for MLB.com since 2015. Follow him on Twitter @FlannyMLB. This story was not subject to the approval of Major League Baseball or its clubs.