KANSAS CITY — For six innings Monday night, Mike Minor was everything the Royals needed and more. The lefty kept the Reds off balance, throwing all his pitches for strikes and limiting the damage to just one run on two hits as he cruised through the sixth inning.

Manager Mike Matheny had no hesitation sending Minor out for the seventh with just 82 pitches thrown and no hits allowed in his last four innings.

The seventh inning was a different story entirely.

Four batters later, the Reds had the lead that would hand the Royals a 6-2 series-opening loss at Kauffman Stadium. It’s the Royals’ second consecutive loss and their 11th in 13 games. One month after they were three games over .500 on June 4, Kansas City is now 14 games under .500 with six more games to play until the All-Star break.

“We know they’re a very aggressive offensive team,” shortstop Nicky Lopez, who was 2-for-4 on Monday night, said. “They have a lot of dangerous weapons up and down their lineup. We know at any moment, those swings can happen. That’s how baseball is, and it swung in their direction. This one got away from us today.”

The Royals’ one-run lead on Jorge Soler’s first RBI since June 14 didn’t last one pitch after the bottom of the sixth inning. Facing the Reds’ power-packed lineup for the third time Monday night, Minor threw a fastball to Nick Castellanos, who hammered it a projected 419 feet to left-center field for the game-tying run.

It was a fastball middle-in that Castellanos swung away on after fouling off three fastballs in his previous two at-bats Monday.

“First pitch to Castellanos, I don’t know why I didn’t think he was going to be aggressive after fouling a couple of balls off his shin,” Minor said. “I thought I could throw something middle-in and he could take a pitch. But he’s a good hitter, and I shouldn’t have taken a pitch off right there.”

Entering Monday, Castellanos had swung at the first pitch 40.7 percent of the time, according to Statcast. After he added to that number, Minor walked both Tyler Stephenson and Joey Votto. The sequence happened in a span of 12 pitches and a mound visit, not giving reliever Kyle Zimmer much time to warm up in the bullpen.

Now 84 games into the season, a Royals starter has recorded an out in the seventh inning in just 11 games and finished the seventh in six. Going seven innings isn’t the only indicator of a good start — a quality start requires at least six innings and three or fewer earned runs allowed — but it does highlight how hard the Royals’ bullpen has been worked halfway through the season.

On the flipside, Minor has an opponents’ batting average of .296 the third time through the lineup this season, with eight doubles and three home runs allowed. But some context is required for those numbers, too. With the way Minor was pitching Monday, the Royals could save their bullpen for the second day in a row, especially during a 20-game stretch without an off-day. He was efficient through six, and perhaps he could have stolen one or two outs before handing things over the bullpen.

“That was leaning in the direction of being one of those really special starts,” Matheny said.

Minor had struck out Castellanos twice before the seventh inning Monday, both swinging on curveballs.

“What don’t you like about 82 pitches and two hits given up?” Matheny said. “Previous inning, [he] had two strikeouts and a groundout. [There] was no hesitation. I would have sent him out in the ninth if that’s where he was sitting. We’ve been looking for our guys to do that all season, and that’s exactly what we needed him to do. But unfortunately, the seventh got us.”

When Matheny handed the ball over to Zimmer with two on and no outs, a 1-1 hanging slider to Eugenio Suárez went a projected distance of 431 feet and landed on the Royals’ Hall of Fame for a three-run lead. Zimmer walked two more and had the bases loaded on a fielding error by third baseman Hanser Alberto before getting out of the inning.

“You try to get ready as fast as possible and get in there,” Zimmer said. “But that’s our job — get going and get hot and try to get out of those situations. And I just hung that one slider and he was all over it.

“I was able to minimize it, but the damage was done.”

For the 12th time this season, and fifth time in their last seven losses, the Royals lost despite out-hitting their opponent. The Reds scored six runs on six hits Monday, while Kansas City knocked seven hits and left eight on base against right-hander Vladimir Gutierrez and Cincinnati’s bullpen.