ARLINGTON -- Rangers right-hander Adrian Sampson did not need an opening act on Sunday afternoon. He also reinforced the belief that he has developed a serious swing-and-miss pitch with his slider. Sampson was sharp from the beginning, and earned his fourth straight victory in a 5-1 win over the Royals

ARLINGTON -- Rangers right-hander Adrian Sampson did not need an opening act on Sunday afternoon. He also reinforced the belief that he has developed a serious swing-and-miss pitch with his slider.

Sampson was sharp from the beginning, and earned his fourth straight victory in a 5-1 win over the Royals on Sunday at Globe Life Park. The Rangers ended up taking three of four from the Royals and have won 12 of their last 18 games.

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Sampson’s last three wins came in relief after the Rangers used an opener in front of him. This time, manager Chris Woodward wanted to see how Sampson looked back in a starting role. The response was overwhelmingly positive.

“That was amazing. Incredible,” Woodward said. “I thought even in the fifth inning he was in complete control. Physically, he wasn’t at his best and he went out there -- that was amazing what he did. It showed me a lot.”

Woodward said he doesn’t foresee using an opener the next time Sampson pitches.

“That’s a pretty good outing to bounce back from,” Woodward said. “I think we need to build some steam off that one, for sure.”

Sampson went a career-high seven innings, allowing one run (a home run by Jorge Soler) on eight hits, no walks and a career-best 11 strikeouts. He is the first Rangers pitcher to strike out 11 without a walk since Cole Hamels on Sept. 19, 2015 against the Mariners. He has won four straight games, but this was the first time he has been the winning pitcher in 11 career starts.

“I mean, I still would have been in the same situation,” Sampson said. “It’s just the first inning. And the first inning was very quick today. I think less than 10 pitches, maybe. So I knew I’d be out there in the heart of it, and it was just good to get a win today.”

The strikeouts reflect the significant improvement Sampson has made with his slider. Nine of 11 strikeouts came on the slider. His previous high for the slider in a game was just four. He also had 13 swings-and-misses overall on the pitch, with the previous high being seven. That was a big question for Sampson entering the season: could he get swing-and-misses?

“That’s something we noticed in Spring Training,” Woodward said. “After a couple of outings in Spring Training, that slider was sharp and he could get some swings and misses. That’s when the conversations started happening, what’s his potential. Today … that’s the best I’ve seen his slider in a few games.”

Sampson’s biggest test came in the fifth inning after Cam Gallagher led off with a single. The Rangers were leading 1-0 at the time. Terrance Gore and Billy Hamilton – two of the fastest players in the game – both dropped bunts and beat them out for hits.

That loaded the bases for the top of the Royals’ order. It was also the beginning of Sampson’s third time through their lineup. Coming into the game, opposing hitters were batting .353 off Sampson in his third time through the lineup.

Not this time. Sampson got Whit Merrifield on a soft liner to third baseman Asdrubal Cabrera, and then struck out both Adalberto Mondesi and Alex Gordon to end the inning.

“I was a little unhappy about it,” Sampson said. “I have my feelings about bunting, but you’ve just got to … it’s part of baseball. You’ve just got to deal with it and just keep making your pitches.”

The Rangers responded with two more runs in the bottom of the fifth. Soler led off the sixth with a homer for the Royals only run. But Sampson held the Royals to a 2-for-9 in the third time through the lineup, and struck out Merrifield in his fourth time up to end the seventh.

“He didn’t miss many spots and when he did, we didn’t take advantage of it,” Merrifield said. “The stuff was pretty good, but he just did a good job locating and we didn’t do a great job capitalizing when he made a mistake.”

Miller earning prime-time spot

Shelby Miller, who began the season as a starter but has since been switched to relief, is earning a prime-time role in the bullpen. Miller got the Rangers out of a bases-loaded jam in the eighth by getting Gallagher on a fly ball to center.

Miller has not allowed a run in his last four relief appearances.

“I’m telling you, he’s got no fear,” Woodward said. “He’s executing pitches a lot better. He made it look pretty easy. He has a low heart rate. Those situations are pretty well-suited for him, so that adds a lot of depth to our bullpen if he’s able to handle those roles. Hopefully we can keep putting him in there and see what we’ve got.”

T.R. Sullivan has covered the Rangers since 1989, and for MLB.com since 2006. Follow him on Twitter @Sullivan_Ranger and listen to his podcast.