Perez has not been placed on the disabled list but is expected to miss at least three games because of inflammation in his right hand, which was aggravated when he batted in Monday night's 7-6 loss to the White Sox. He left the game after eight innings.
"It got so swollen and sore yesterday, we had to do something. Give him some time because it's not going to get any better playing," manager Ned Yost said. "So take two, three, four days off and let the trainers work on it, get that inflammation and swelling out of there. When you get jammed like that and get all puffed up, it's really painful."
So that puts Perez out of the rest of the White Sox series and perhaps into the second game of the Angels series, which starts Friday night at Anaheim.
"I'm optimistic for Saturday. I'm not really sure I want to do it on Friday with C.J. Wilson pounding cutters in on his hands the whole time," Yost said. "So, when we get there, we'll figure it out."
Pena will back up Brett Hayes, who moved into the starting lineup on Tuesday night against the White Sox. Pedro Ciriaco takes over at second base for Giavotella who, in turn, was subbing for injured Omar Infante.
For Omaha, Pena has socked nine home runs and three doubles with 15 RBIs and a .240 (24-for-100) average in 30 games.
Often called Frank or Frankie, Pena is the son of former Royals manager and current Yankees coach Tony Pena and the brother of former Royals shortstop and now Mexican League pitcher Tony Pena Jr.
"He's a young kid that brings a lot of enthusiasm," Yost said. "In Spring Training, he did a great job defensively for us. He's an average thrower, does a great job of calling a game and receiving the ball. He has some power -- he has nine home runs in Triple-A -- and he's here for the next four or five days in case something happens to Hayes, we've got some backup."
This was Giavotella's second stay with the Royals. He was with the club just three days in April and then was recalled on May 9. In a total of 10 games, Giavotella had a .176 (6-for-34) average with one homer, a game-winner at Seattle, and five RBIs. He had a .352 mark at Omaha.
Ciriaco, also in his second stint this year, had played in just five games previously. He was kept because he provides protection behind shortstop Alcides Escobar.
"I need a backup at short," Yost said. "Giavotella can play second, he can't play short. We've got [Mike Moustakas or Danny Valencia] who can fill in at second to get us through a game, but I've got to have a shortstop."
Infante's 15 days on the disabled list expire on Thursday, but it's not known when he'll be ready to return.
"He's starting to get over the hump and went through some simulated fielding drills today, and they're going to do some more a little bit later," Yost said. "He's definitely making progress."