Dyson went on the disabled list with a high ankle sprain and is expected to be out two-to-four weeks. Dyson sprained his right ankle while scaling the wall in a futile attempt to catch a Mike Trout home run on Wednesday.
Lough was summoned from Class AAA Omaha to not only take Dyson's roster spot, but to bat leadoff when he starts in the outfield.
Lough was hitting .340 with a .393 on-base percentage in 36 games in the Pacific Coast League while batting leadoff. He also put together a 16-game hitting streak.
"He had a great spring and went down, did what you ask all young guys who have good springs to do -- he continued it," said manager Ned Yost, whose Royals lost to the Astros 6-5 Monday. "He's been hot and doing well."
Lough, who was an 11th-round draft pick in 2008, hit .237 in 20 games last year with the Royals after a September promotion, his first time in the majors.
"This is his second run through the big leagues," Yost said. "He's got some experience and a little bit of a feel for what it's like. It could be good for him."
Lough, however, went 0-for-4 Sunday in a 4-3 loss to the Athletics and committed a costly error that led to an unearned run. He did not play in Monday's loss.
Dyson was the first player the Royals put on the disabled list since the season started.
NEXT: Royals (Wade Davis, 3-3, 5.98) at Astros (Bud Norris, 4-4, 4.32)
C Salvador Perez departed in the sixth inning on Monday after experiencing discomfort in his right hip. With the Astros batting in the bottom of the fifth, Perez slid into the railing of the Houston dugout pursuing a foul ball. He remained in the game following a visit from team trainers, but exited at the inning break. He finished 1-for-3.
RHP Wade Davis will make his ninth start of the season in the middle game of a three-game series with Houston. Davis earned his first win in four weeks last Wednesday, a 9-5 decision over the Los Angeles Angels, allowing four runs on nine hits and three walks over 5 1/3 innings. Davis is making his second appearance against the Astros in Houston, having earned a 7-2 victory at Minute Maid Park on June 25, 2011.
3B Miguel Tejada made just his second appearance of the Royals' current nine-game road trip and finished 1-for-4 with a three-run home run in the fourth inning. The homer was the first for Tejada over a span of 50 at-bats dating back to July 16, 2011 against the San Diego Padres. Tejada was with the San Francisco Giants at the time, and he did not appear in the majors last season.
RHP Jeremy Guthrie lasted just five innings against the Astros, allowing six runs on eight hits (including two home runs) and three walks with two strikeouts.
LF Alex Gordon extended his hitting streak to eight games with a single in the top of the first inning. Gordon finished 1-for-3 with a pair of walks, and is batting .469 (15-for-32) during the streak.
RF Jeff Francoeur finished 3-for-4 with an RBI double and a run scored. The three-hit game was his first since Sept. 23, 2012 against the Cleveland Indians. Francoeur also went 3-for-4 with a double, an RBI and a run scored in that game, a 15-4 loss.
"We had some opportunities where if we got a big hit, who knows? Anytime you lose a one-run game, you go back and look at the opportunities where you missed throughout the game. There were no glaring opportunities, but the way things are going right now, we're struggling to get that hit."—Manager Ned Yost, after the Royals lost to the Astros 6-5 Monday.
C Salvador Perez (hip injury) left in the sixth inning of the May 20 game.
CF Jarrod Dyson (sprained ankle) left the May 15 game. He was placed on the 15-day disabled list on May 17, retroactive to May 16. Dyson is expected to miss two-to-four weeks.
LHP Danny Duffy (Tommy John surgery in June 2012) went on the 15-day disabled list March 31. He threw 15 pitches in an extended spring training game in Arizona in late April. He is on schedule to pitch five innings by June 13, the one-year anniversary of his surgery.
RHP Felipe Paulino (Tommy John surgery in July 2012) went on the 60-day list Feb. 12. He threw 20 batting practice pitches the week of April 22. Paulino is out of options, so he can only pitch with a minor league affiliate for 30 days if he goes on a rehab assignment.
RHP James Shields
RHP Ervin Santana
RHP Jeremy Guthrie
RHP Wade Davis
RHP Luis Mendoza
RHP Greg Holland (closer)
RHP Aaron Crow
RHP Kelvin Herrera
LHP Tim Collins
RHP Luke Hochevar
LHP Bruce Chen
RHP J.C. Gutierrez
1B Eric Hosmer
2B Chris Getz
SS Alcides Escobar
3B Mike Moustakas
DH Billy Butler
INF Miguel Tejada
LF Alex Gordon
CF Lorenzo Cain
RF Jeff Francoeur
OF David Lough
OF/INF Elliot Johnson