• John Lamb, the Royals' No. 14 prospect according to MLB.com, was promoted to Triple-A Omaha on Tuesday after 19 starts with Class A Wilmington.
Lamb, the club's fifth-round pick in the 2008 First-Year Player Draft, is 4-12 with a 5.63 ERA in his first full season following 2011 Tommy John surgery.
• The Kansas City bullpen continued its tremendous homestand with three more scoreless innings in Monday's 6-2 win over the Marlins.
Entering Tuesday, Royals relievers had allowed just one run in 23 innings since the 10-game homestand began on Aug. 5 with three games against the Twins, combining for a 0.39 ERA and 29 strikeouts.
Moustakas diagnosed with strained left calf
KANSAS CITY -- Royals third baseman Mike Moustakas went through tests on Tuesday morning to confirm that he has a left calf strain. He is listed as day to day, but is not expected to play in Wednesday's series finale against the Marlins.
"He feels better today," Royals manager Ned Yost said. "He was hobblin' but he's not hobblin' today. It wasn't hobblin'. He had a slight little limp and with a couple of days of treatment, we'll see where he's at. I don't know."
Moustakas beat out an infield single to first base in the fourth inning and started to feel some tightness in his calf after rounding third base to score on Justin Maxwell's triple. After playing defense in the top half of the fifth, Moustakas was lifted for pinch-hitter Jamey Carroll, who stayed in the game at third base.
"It was a lot more sore when I woke up this morning," Moustakas said. "Yesterday, it was feeling all right with the adrenaline, but today it was a little sore. I went and got a lot of treatment today and it feels a lot better. I'm able to walk around on it and put some pressure on it."
This is the second calf injury in three days for the Royals, who placed infielder Miguel Tejada on the disabled list with a strained right calf on Monday.
"I've never felt anything like that before, but it feels a lot better today," Moustakas said.
Moustakas has been a big part of the Royals' run to a 19-5 record since the All-Star break, hitting .293 in that stretch with 13 RBIs after batting just .215 previously.
Yost gives Salvy break amid marathon stretch
KANSAS CITY -- Catcher Salvador Perez was not in the Royals' starting lineup on Tuesday night against the Marlins. Nothing wrong with him, just getting a break.
"We're 14 days into a stretch where we play 44 games in 44 days," manager Ned Yost said. "With a day game coming tomorrow, give him a break where you can afford to give him a break."
Perez did catch the 10th and last inning as the Marlins scored the only run to win, 1-0, and he fouled out for the second out of the Royals' half of the inning.
Perez will be back in the lineup on Wednesday afternoon against the Marlins. He had missed a week because of a low-grade concussion and returned to play Sunday and Monday with no problems.
"He's feeling good. Went out and took a bunch of early hitting today," Yost said.
With a crucial five-game series at Detroit coming up, Yost wanted him ready to go. Perez is likely to catch four of the five games, skipping one of the two games to be played on Friday. Perez will catch whichever game of the doubleheader that James Shields pitches.
Perez's concussion came as a foul ball struck his protective mask and he decided to test the more elaborate hockey-style mask in the two starts since his return from the disabled list.
"Pretty good, but I don't like it as much as the other one," he said.
Even so, the All-Star plans to try the hockey mask some more before making a decision.
Duffy likely in mix for start in Friday's twin bill
KANSAS CITY -- The Royals still haven't announced a second starting pitcher for Friday's day-night doubleheader at Detroit, but manager Ned Yost indicated he'd make his decision public on Wednesday.
There was a strong indication that left-hander Danny Duffy would return for that duty because, on Monday night, he made an abbreviated start in Triple-A Omaha's 11-inning, 5-4 win over Fresno. He pitched only the first inning, retiring all three batters on 10 pitches with two strikeouts.
Duffy, coming back from elbow surgery, made his first Royals start in more than a year last Wednesday night -- going 3 2/3 innings in a 5-2 victory over the Twins.
Right-hander James Shields will pitch one of the two games on Friday and so will Tigers ace Justin Verlander. Yost also hasn't yet revealed whether or not he'll match up Shields with Verlander.
Royals running on with tremendous success
KANSAS CITY -- The Royals have been more aggressive on the basepaths of late and they led the American League with 93 stolen bases entering Tuesday's action. Kansas City runners logged eight steals in the previous three games and had stolen nine straight.
"It's a huge part of our offense," second baseman Chris Getz said. "Certain teams are put together in different ways and with the ballpark that we have and the pieces of this team, stealing bases is important."
The Royals also lead the Majors with an 82.3 percent success rate -- having been caught just 20 times. Only the Milwaukee Brewers (105) have more stolen bases among big league clubs.
"We've got aggressiveness with success so that's a positive and it's just creating more offense, more movement, more holes, putting guys in scoring position," Getz said. "I think it's really benefiting our team and the success rate is huge."
The Royals have four players with double-digit steals totals led by Jarrod Dyson's 18. Alcides Escobar and Elliot Johnson have a perfect slate with 14 and 13, repectively, without having been caught. Lorenzo Cain is next with 12, while Getz and Eric Hosmer each have nine.
Paulino struggles in second start for Omaha
KANSAS CITY - Right-hander Felipe Paulino labored through 3 1/3 innings on Tuesday night in his second rehab start with Triple-A Omaha.
Paulino, who is recovering from Tommy John surgery in July 2012, allowed five runs on eight hits with two walks and two strikeouts in Omaha's 7-3 loss to Fresno. He threw 75 pitches -- 47 strikes. Through two starts with the Storm Chasers, he has a 9.95 ERA with nine runs allowed (seven earned) on 13 hits to go with three walks and six strikeouts.
Paulino started his rehab assignment on June 11, but was sidetracked by lower back and shoulder stiffness.
Dick Kaegel is a reporter for MLB.com. Kathleen Gier is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.