HOUSTON -- Kansas City Royals closer Wade Davis is dominant far more often than not, a fact that made his control woes in the ninth inning Tuesday night noteworthy until he unleashed his 33rd and final pitch.

Davis survived a tense final frame after a resilient performance from starter Kris Medlen, and the Royals eked out a 3-2 victory over the Houston Astros at Minute Maid Park.

En route to his third save of the season, Davis issued one-out walks to Luis Valbuena and Jason Castro before running the count full to Astros second baseman Jose Altuve. Davis then induced a fly out to right from Altuve before getting a called third strike on a cutter to George Springer.

"(My control) was definitely off a little bit," Davis said. "Just feeling it out, rushing a little bit, couldn't really get back to a good rhythm. In a one-run game, you're not really going to give in at that point, especially with runners on. You're not trying to give up the lead and lose the game."

Medlen (1-0) made a three-run Royals first inning stick by stranding five runners during his five-inning outing. He was effective enough to hand over a lead to the vaunted Kansas City bullpen, which followed with four scoreless frames.

The Royals (5-2) squared the four-game series at a game apiece despite Davis' issues. Right-handers Luke Hochevar and Kelvin Herrera each threw a perfect inning after Medlen exited. Joakim Soria worked around a single and a walk in the eighth before Davis took over.

"It's a real comfort level knowing that if your club is tied or has the lead after the fifth inning you feel like you're going to win," Royals manager Ned Yost said of his relief corps. "It was evident again tonight.

"You come in Hoch, Herrera, Soria, Wade Davis -- it's a really nice feeling for everybody because it takes pressure off everybody. They know that we don't have to score 10 runs to win a baseball game. We've just got to score one more than they do and get it past the fifth inning, and our guys are going to get after it."

Lorenzo Cain smacked his second home run of the season in the first inning, a three-run shot off Astros right-hander Mike Fiers (0-1) to provide the Royals all the offense they would need.

Fiers recovered and did not allow more than one baserunner in any of his remaining five innings. He benefited from a nifty double play started by first baseman Tyler White after Eric Hosmer reached to open the sixth. Fiers got a groundout to close the inning and capped his night having allowed three runs, six hits and one walk with three strikeouts in six innings.

"I need to make better pitches there," Fiers said. "All I can do is move on and pitch well after that. Just need to clean up that first inning; other than that, I felt good."

Like Fiers, Medlen had a shaky start, only to rebound quickly. He faced seven batters in the first, allowing an RBI double to Colby Rasmus and a run-scoring single to White that cut the lead to 3-2. However, Medlen limited the damage by coaxing Carlos Correa to ground into a double play.

In the third, Medlen picked off Springer after a single and induced Rasmus to hit into an inning-ending double play, facing the minimum despite allowing two hits. In giving way to Hochevar, Medlen departed having allowed two earned runs, six hits and four walks. His seventh strikeout closed the fifth, Rasmus whiffing with two runners on.

"We had first and second with two outs a couple of innings and didn't come away with the big hit," Astros manager A.J. Hinch said. "And first and second with one out at the end and couldn't pull one across."

The Astros (3-5) left nine runners on base and finished 2-for-10 with runners in scoring position.

NOTES: Astros DH Evan Gattis (hernia) returned from a season-opening stint on the 15-day disabled list and finished 0-for-4 with three strikeouts while batting seventh. Despite the Royals starting RHP Kris Medlen, the right-handed-hitting Gattis was in the lineup instead of lefty-hitting Preston Tucker, who is batting .333/.412/.933 in six games. ... Royals OF Jarrod Dyson, out since the first spring training game, had a scheduled day off Monday as he continues his injury rehab stint with Triple-A Omaha. Dyson, sidelined by a right oblique strain, returned to Omaha's lineup in right field Tuesday and went 2-for-5. ... After Astros RHP Lance McCullers made the first start of his rehab assignment Monday night with Double-A Corpus Christi, he was in Houston on Tuesday completing a bullpen session. He will make a second rehab start Saturday with Corpus Christi.