HOUSTON -- With innings counts and future health weighing his mind, Houston Astros manager A.J. Hinch resisted the urge to trot left-hander Dallas Keuchel back out to the mound for the ninth inning on Tuesday night, even with Keuchel having a tendency to make such decisions difficult.

Keuchel tossed eight shutout innings and made a convincing argument to start for the American League in the All-Star Game in the Astros' 4-0 victory over the Kansas City Royals at Minute Maid Park.

Keuchel (10-3) joined Mariners right-hander Felix Hernandez as the only American League pitchers with double-digit wins. On the heels of hurling his third career shutout last Thursday night against the Yankees, Keuchel scattered seven hits and recorded seven strikeouts without issuing a walk. He dominated Kansas City (44-30) in front of Royals manager Ned Yost, the American League manager for the All-Star Game.

"He utilized both sides of the plate really effectively," Yost said of Keuchel. "He'd get us looking away and then he'd start pounding us in. We couldn't gauge him. He was changing speeds. He really did a great job of keeping the ball down."

After requiring 116 pitches to complete what he started in his previous outing, Keuchel had 106 pitches on his ledger at the close of the eighth inning. That workload prompted Hinch to act in the best interests of his ace, no matter how ferociously Keuchel champs at the bit.

"It's never easy to take Dallas Keuchel out of the game, but I've got to manage the short term and long term," Hinch said. "I think Dallas had done his job. He was a little tired in my eyes, probably not in his eyes.

"We know he likes to finish games. The complete-game shutout would have been cool for a lot of people but it's a tough call all the time. Most importantly, we need to get through the game and get done, and have everybody feel good on the accumulation over the season."

Right-hander Pat Neshek worked the ninth inning, allowing a one-out single to designated hitter Salvador Perez yet preserving the shutout.

The Astros (46-34) clustered their runs over three innings against Royals left-hander Danny Duffy (2-4), who was one strike away from facing the minimum through three innings when Astros third baseman Marwin Gonzalez singled on an 0-2 pitch with two outs in the third.

Suddenly, things began to crumble for Duffy, starting with a two-run homer by Astros center fielder George Springer after the Gonzalez hit.

"I think I was most upset about hanging the slider to their nine-hole guy (Gonzalez)," Duffy said. "But I just tried to throw hard and make it really tight. But it just floated in there. I think that may have taken me out of the next at-bat, which is in my opinion the best hitter on their team."

The Astros built their lead to 3-0 when designated hitter Evan Gattis scored on a wild pitch with one out in the fourth after tripling to straightaway center. With one out in the fifth, Duffy walked Springer and then allowed an RBI double to Astros second baseman Jose Altuve.

Keuchel allowed two-out hits in each of his first three innings yet managed those speed bumps with ease. By keeping the bases clear in advance of those late-inning hits, Keuchel easily negated any damage and, as usual, the groundball out proved his most effective weapon.

He closed five of his first six innings with groundouts, including an inning-ending double play off the bat of Royals shortstop Alcides Escobar in the fifth inning. He retired the side in order only once through those six innings, yet Keuchel remained in complete control.

"I try to get as many ground balls as possible, keep their job easier, keep them fresh," Keuchel said of his infielders. "I have some pretty fresh legs, so hopefully I can keep that up."

NOTES: Astros RHP Scott Feldman threw a three-inning simulated game against OF Jake Marisnick and 1B Jon Singleton and is prepared to depart for a rehab assignment. Feldman will throw a bullpen session later this week before pitching with an affiliate this weekend. He has been on the 15-day disabled list since May 27 following right knee surgery. ... Marisnick will begin a rehab assignment on Wednesday with Triple-A Fresno in El Paso. Marisnick has been on the 15-day disabled list since June 19 with a left hamstring strain. ...Royals OF Jarrod Dyson sat out Tuesday night as he continues to manage a sore left groin suffered last week in Seattle. The injury is considered minor, however, and Dyson should return to the lineup on Wednesday.