Royals manager Ned Yost named Almonte his starter on Wednesday -- the same day right-hander Nathan Karns (forearm soreness) was placed on the 10-day disabled list. Thursday would have been Karns' spot in the rotation.
Outfielder Alex Gordon, back from paternity leave, took Karns' spot on the 25-man roster.
Almonte, who was called up Sunday, is 1-0 with a 2.17 ERA in seven games, six starts, for Double-A Northwest Arkansas this season.
Almonte said he already had some nerves about the start, but that teammates have been guiding him through the anxiety.
"Vargy [Jason Vargas] was telling me to just do the same thing I've been doing," Almonte said. "Throw strike one and just go out and pitch."
The Royals made Karns' DL move retroactive to Sunday, meaning he won't be able to be activated until next Wednesday.
"We'll need another starter on Tuesday then," Yost said. "We'll figure it out later."
Gordon was back after returning from Kansas City where his wife, Jamie, gave birth to their third child on Monday, a girl named Joey Lynn.
"They're not back from the hospital yet," Gordon said. "But I can tell you it's incredible to have another child."
The Gordons have two young boys, Max and Sam.
On the subject of having a baby girl, Gordon smiled and said, "They say they soften you up, then steal your heart."
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.