KANSAS CITY — Five of Ian Kennedy’s six innings were sharp, but his shaky third frame was the difference in the game.

Kennedy gave up five runs and four hits in the Royals’ 6-3 loss to the Rangers on Monday night at Kauffman Stadium, with four runs coming in the third inning. After opening the third with a strikeout, Kennedy walked two and allowed a single before Adrian Beltre sent a first-pitch knuckle curve flying for a three-run homer.

“The pitch to Beltre was a mistake,” manager Ned Yost said. “He got a curveball up and out over the middle of the plate there, and Beltre hit it out of the park. But outside of that, I just thought he was really, really good.”

Kennedy allowed just two hits outside of that third inning, one of which was a Shin-Soo Choo leadoff homer. But the damage was done.

“One really bad inning,” Kennedy said. “Cost us the game. One pitch, hung a curveball, that three-run homer’s the big swing. I felt like I pitched better than the line, but it just doesn’t matter when you make one bad pitch and it costs you the game.”

It was the Royals’ seventh loss in a row, and their 13th in 14 games.

Kennedy settled in after Beltre’s blast, retiring 11 of the final 13 hitters he faced and striking out eight overall.

Wily Peralta made his Royals debut in relief after replacing Brian Flynn in the seventh. Peralta allowed one run and walked three in 1 1/3 innings.

Adalberto Mondesi’s RBI double scored Abraham Almonte and Mondesi came home on a sac fly by Mike Moustakas. It was Mondesi’s first start since being called up from Triple-A Omaha on Sunday.

Rosell Herrera, making his first start as a Royal, knocked in a run in the fourth with a triple to deep right field.