KANSAS CITY -- There were pitching problems galore for the Padres on Sunday. It started with Sean Manaea and ended with Josh Hader.

With hopes of sealing a series sweep against Kansas City, it was an uphill climb for San Diego all day. Manaea surrendered seven hits and five runs in the first inning and the Royals went on to a 15-7 victory at Kauffman Stadium, forcing the Padres to settle for two-of-three in the weekend set.

San Diego got away with a rough first inning from its starter once in the series, but not twice. Whereas Yu Darvish pulled it together after allowing three runs in the first on Saturday, Manaea lasted just four innings after the Royals knocked him around in the first.

But perhaps the most alarming development was Hader’s appearance in a low leverage situation with San Diego trailing 9-6 entering the bottom of the eighth. Hader allowed five hits and six runs while retiring just one Kansas City hitter.

With Hader at 34 pitches and having just allowed a two-run single to Michael A. Taylor, manager Bob Melvin removed one of the game’s most dominant relievers in recent memory in favor of position player Wil Myers, who jogged in from left field to take the mound.

“It’s hard,” Melvin said while talking about Hader. “Certainly hard for him. It looks like hitters are getting a good look. You aren’t seeing the swings and misses that you normally do, both with the heater and breaking ball.”

In his previous outing against Cleveland, Hader had been encouraged by a performance in which he struck out the side, although allowing two hits.

“Just working through it,” Hader said. “You are going to have good ones and bad ones. Trust the process.”

While the Padres are hoping Hader will be able to find the closer form that once made him so imposing for Milwaukee, they also will be looking for consistent quality from Manaea as they head down the stretch in search of a Wild Card playoff spot.

“It’s frustrating,” Manaea said. “I hold myself to a pretty high standard. This year hasn’t really been up to that. But what can you do? As long as I’m healthy and able to throw the ball I think I’ll figure it out.”

The lopsided loss came on a day in which third baseman Manny Machado did everything he could to try and pull the Padres out of a 5-1 hole in the first. Machado finished 4-for-5 with two homers, a double and four runs batted in. Juan Soto also went deep, cranking a two-run shot in the seventh.

“[Machado] had a great day at the plate,” Melvin said. “Just continues to put up good offensive numbers. He’s usually right in the middle of everything.”

The Padres drew within two on Machado’s two-run homer in the fifth. It would have been a three-run homer if catcher Luis Campusano hadn’t been picked off second just moments before Machado’s second homer of the day.

“He’s trying to get in position to score,” Melvin said. “Got a little too enthusiastic out there.”

The Padres headed on to San Francisco after Sunday’s disappointing series finale, and they’ll try to get back on solid footing Monday night with right-hander Mike Clevinger on the mound.

“It seems like we take a couple of steps forward and today we certainly took a step back,” Melvin said.