CINCINNATI -- As he kept racking up strikeouts at a historic rate, Nick Lodolo provided the stopper-esque start the Reds have desperately craved all week. Yet, the rookie was still down on himself for one costly mistake.

A 10-4 loss to the Pirates on Wednesday at Great American Ball Park completed a four-game series sweep of Cincinnati, which has dropped six consecutive games. For the second straight start, Lodolo reached a career high with 11 strikeouts and no walks, while pitching 6 1/3 innings.

But Lodolo was done in by a three-run home run from Rodolfo Castro in the third inning. The other seven runs were scored against the bullpen over the final three frames.

"It’s hard to forget about that one pitch," said Lodolo, who gave up five hits and hit one batter.

Since 1893, Lodolo and Dwight Gooden (1984) are the only rookies to have consecutive starts consisting of no walks and at least 11 K's.

"He's punching guys out left and right. It's fun to catch. You know we're going for strikeouts, we're going for dominance," said Reds catcher Austin Romine, who hit a two-out solo homer in the fifth.

It marked the first time any Reds starter delivered back-to-back 11-strikeout performances since Jose Rijo in 1994, and Lodolo is the first rookie to do it since Bruce Berenyi in 1981. The 24-year-old's rate of 11.65 strikeouts-per-nine innings is the highest in Major League history by a left-handed rookie starter.

"It’s cool, but at the end of the day, I’m more pissed off today about giving up the three-run bomb that helped jump start their day a little bit," Lodolo said.

Over his last five starts, Lodolo is 1-2 with a 2.72 ERA, six walks and 49 strikeouts over 39 2/3 innings. He has allowed one walk with 31 strikeouts over his last three outings.

"The beginning of the year, I was walking a lot of guys, which I’m not used to doing," said Lodolo, who is 4-6 with a 3.81 ERA in 16 starts this season. "That’s what I pride myself on, really just trying to fill up the zone. Now I feel like I’m really starting to do that, and the results just come with that."

The not-so-secret sauce that made Lodolo effective was again his curveball, which he went to repeatedly against Pittsburgh. Statcast data showed that he used it 42 times out of 102 pitches. Of the 25 swings, it got 13 misses with an additional seven called strikes.

"I wouldn’t say I had the best command of the fastball today, but you have to give credit to Romine," Lodolo said. "The guy, whatever I’ve got that day, he finds a way to get me through it."

Lodolo has a sweeping curveball, especially against right-handed hitters, that can often hit them in the foot -- which happened on an 0-2 pitch to Diego Castillo in the second inning. Romine didn't think the pitch was comparable to others he's caught.

"I think he's very unique for what he does. He has his own arm angle, his own pitch," Romine said. "It just keeps going. Righties have trouble with it; it looks like it's going to stop and break down, and it just keeps chasing them inside. Some of these guys are swinging at curveballs that almost hit their back leg. That tells you something right there that he's got a really good breaker."

The curveball was Lodolo's strikeout pitch eight times Wednesday. It was also a pitch that hurt him. Following Bryan Reynolds' one-out single in the third inning, Castro’s three-run homer to left field came off a 2-2 curveball, and it was the only extra-base hit Lodolo gave up.

"I think I had got him on it before, the first-bat, and I was just trying to do the same thing," Lodolo explained. "Trying to get it down to the back foot and just hung it. [Castro] did what he was supposed to do."

Lodolo, who missed more than two months with a back strain and returned on July 5, is on pace to finish strong in his first big league season.

"More than anything before this [stretch] started, you just really saw his presence grow on the mound within the team. Confidence. It’s very exciting," Reds manager David Bell said. "Now he’s at a point where we’re getting close to the end and he can take this into the offseason. I know he’s got some work to do here the rest of the way.”