Brad Keller entered Thursday’s series opener against the White Sox looking for a rebound after a shaky Opening Day start. But another long and laborious first inning hurt the Royals’ right-hander for the second start in a row.

Keller allowed back-to-back home runs in the first inning of the Royals’ 6-0 loss at Guaranteed Rate Field, and was tagged for four runs in 3 1/3 innings overall in the White Sox home opener. The short start was a continuation of his struggles from Opening Day, when Keller allowed six runs in 1 1/3 innings.

“I just feel like I haven’t had the same conviction behind the pitches,” Keller said. “Being a little timid, especially going in on some guys, trying to place some balls instead of throwing through the catcher. Trying to be so fine and making the perfect pitch instead of just going after guys and letting them get themselves out.”

After a two-hour, 12-minute rain delay, Keller got two quick outs in the bottom of the first, but allowed a double from reigning American League MVP José Abreu. Keller proceeded to allow back-to-back home runs to Yoán Moncada and Yermín Mercedes.

Both home runs were on sliders that Keller wanted to throw down and away. Instead, both started up out of his hand and stayed over the plate. Moncada took his 421 feet over the left-center-field wall.

Mercedes took his 485 feet.

Keller was able to settle down after allowing his fourth run in the second inning. His last four outs were on the ground -- where Keller thrives with his sinker -- and he got through a scoreless third inning with a key double-play ball. But the damage was done. He exited with one out in the fourth inning after walking Danny Mendick and throwing 69 pitches.

“I finally put up my first zero of the season on the bright side,” Keller said of his third inning. “I felt like after that double play, I got some confidence back. I just felt like I had a little bit of momentum. Then got the first out in the fourth, and then walked a guy. I tried to go after him, tried to nibble with a 3-2 fastball and missed.”

That “nibbling” with the fastball is something Keller must fix as he looks to turn around the early part of the season. Keller flourishes off ground balls and weak contact with his fastball, and that requires pounding the zone -- especially the inner half. He registered just two whiffs on his sinker and none on his four-seamer, with the weak contact he relies on not coming until later in his outing.

“I think I just have to go back into attack mode,” Keller said. “ Just got to keep going at guys. I got to doing what I did best in previous years, and that’s pitching to the skinny part of the bat and getting weak contact and keeping the ball on the ground. I’m just trying to do too much right now.”

What Keller couldn’t do Thursday is what White Sox starter Lance Lynn did all night -- establish his fastball and work off it. Lynn pitched his second career big league shutout -- his first came in 2014 for the Cardinals and then-manager Mike Matheny -- and he had a perfect game going until Salvador Perez’s infield single in the fifth inning. Lynn thrived off strikeouts (11) and flyouts (11) while holding the Royals to five singles. Over 67 percent of the 111 pitches Lynn threw were either his sinker or four-seamer, and another 27 percent was his cutter, according to Statcast pitch tracking.

“It was hard sink, hard cut, trusting his movement,” Matheny said. “Probably a lot like the conversation that we’ve already had with Brad. He’s got the ability to predominately use that pitch and use the other pitches off of it. And [Keller has] just got to trust it a little bit more, like we saw on the other side. He [Lynn] trusted it.”

Two starts into the season is not a time to start panicking about Keller, but he and the Royals know he has to turn things around soon.

“Never want to get too far ahead of yourself,” Matheny said. “Right now, it’s two outings that didn’t go anything like how he wanted them to go. He’s going to make those adjustments, jump right back in there.

“But even as I told him as he was walking off the mound today: ‘We’ve got all the faith in the world in you that you’re going to get this figured out. And you’re going to come back and you’re going to lead this staff.’ And that’s exactly what I want him to believe.”