KANSAS CITY — Chalk it up as another learning experience for Royals rookie right-hander Jorge Lopez (aka Lopie for Players’ Weekend).

Lopez, making his third start for the Royals since being acquired from the Brewers in the Mike Moustakas trade last month, breezed through the first three innings on Sunday against the Indians at Kauffman Stadium.

Lopez gave up one hit and one walk through three scoreless innings, mixing in a sharp-breaking curveball with four-seam and two-seam fastballs. But after striking out Jose Ramirez (Enriquito) to open the fourth, Lopez completely lost command and gave up two walks, four hits and five runs. The Royals went on to lose, 12-5, on the final day of Players’ Weekend.

“I think he got a little tired,” Royals catcher Drew Butera (Vito) said. “Hot day, and I don’t know if he’s been used to that. He went through the first couple of innings nicely but worked a lot. Then got a little tired and left a couple pitches over the plate.”

Lopez admitted, too, that he got fatigued in the hot weather, as the heat index neared 100 degrees.

“After 20 or 25 pitches [in the fourth] I got a little tired and it got worse,” Lopez said. “You battle with yourself. I need to get deeper into games, and I couldn’t do it today.”

Royals manager Ned Yost noticed Lopez’s command of all of his pitches leaving him in that fourth inning.

“He made a series of mistakes that they didn’t miss,” Yost said. “Found the heart of the plate, and they just didn’t miss it.

“I mean, he was commanding them fine — commanding them kind of down the middle of the plate. The walks definitely hurt him. He fell behind in the count. But every time he’d fall behind, then he’d try to make a pitch, and it was just a little too fat in the zone. They hit it.”

Lopez, who left after four innings and 79 pitches, walked three and struck out four. And Lopez said afterward he is continuing to make the adjustment from the bullpen back to the rotation, where he pitched almost exclusively in the Brewers’ organization until last season, when Milwaukee made him a reliever.

“It’s a completely different animal [than being in] the bullpen,” Lopez said. “I’m still getting to the point where I’m learning. I’ll get to six or seven innings, which the Royals need.”

Whit Merrifield (Whitley) had given the Royals a 1-0 lead when he led off the first inning with his 10th home run of the season, smacking a 3-2 fastball from right-hander Shane Bieber (Not Justin) an estimated 430 feet, per Statcast™, to left-center field. It was Merrifield’s fifth career leadoff home run and second this season (July 2 against Cleveland).

Salvador Perez (El Nino) added his 23rd home run leading off the fourth. Lucas Duda (Dude) belted a two-run home run, his 13th, in the sixth.