Cueto, a noted Pirates tamer, pitched hitless ball until Brandon Inge singled on a soft liner to left with one out in the fifth.
"It was kind of an excuse-me hit, but I'll take a one-hitter all night," Cincinnati manager Dusty Baker said of Inge, who had been a late lineup addition when Pedro Alvarez had to be scratched due to the aching reminder of having had two wisdom teeth extracted on Thursday.
"Luckily Brandon saved us all with that half-swing base hit," said Neil Walker, who made the final out as reliever Sam LeCure closed out the game with a perfect ninth. "We should've all tried it. Nothing else seemed to work for us."
Wandy Rodriguez answered the Cueto challenge with one of his better starts of the season, but two of the five hits the left-hander allowed in seven innings were solo home runs.
"A very professional effort from Wandy," manager Clint Hurdle saluted. "He gave us what we needed. Kept us in the game."
The loss, only the third in 12 games for the Pirates, dropped them back into a second-place tie with the Reds, with both teams trailing National League Central leader St. Louis by two games. The Bucs had also won 10 of their last 11 home games.
It was the first Pittsburgh defeat in more than a month that could be classified as a "blowout." The last time the Bucs had lost by more than four runs was in late April, defeats by 9-1 in St. Louis and 10-4 in Milwaukee.
Cueto picked up where he left off six weeks ago, when he was on his typical PNC Park cruise, having held the Pirates to two hits through 4 1/3 innings before leaving with a strained side muscle. That injury sidelined him for more than a month, and Friday's effort was the best of his three comeback starts.
"It was the same guy we've seen before: He threw strikes -- sinkers, cutters, changeups, both sides of the plate," said Walker, who claimed the hardest-hit ball off Cueto, a sixth-inning liner that was in first baseman Joey Votto's glove practically before Walker had even stepped out of the batter's box.
"I don't care [how hard I hit that ball]. It was an out," Walker said, with a bemused grin. "I don't know … you hit a ball that hard … sometimes you feel like it's the guy's night. This was one of those. You tip your cap. I hate to use those words, but he was really good tonight."
The only time the Pirates put two men on base was in the first inning, and they had little to do with it: Cueto walked Walker on a full-count pitch, and his next offering bounced off Andrew McCutchen's left shoulder. Walker, who moved to third as Garrett Jones bounced into a force, was the only Pittsburgh baserunner beyond first base.
With the dominant performance, Cueto went to 8-2 in PNC Park (with an ERA of 1.90) and 13-4 overall against the Pirates. In his eight innings, he allowed a walk while striking out six.
Jay Bruce solved Rodriguez -- against whom he had been 2-for-33 lifetime -- for a solo shot into the right-center stands with one out in the fourth, then Brandon Phillips made it 2-0 with a line drive over the 325-foot left-field wall leading off the sixth.
"I don't know if I believe in being due," Bruce said "I just think I'm a better hitter and he gave me a pitch to handle. I take nothing away from him. He still goes out there and gets the job done. I'm a better hitter than I have shown against him in the past."
In his seven innings, Rodriguez also walked three and struck out five.
The Reds added on in the eighth against Mike Zagurski, the left-handed reliever who did not leave a good first impression on the PNC Park crowd. In his home debut with the Pirates, Zagurski endured a nightmarish inning which he began by hitting Phillips. Before it ended, he uncorked a run-scoring wild pitch and surrendered an RBI single to Derrick Robinson that made it 4-0. Zagurski returned for, but couldn't finish, a ninth inning in which he was charged with two more runs.
While reasonably pointing out the exceptional pitching his boys have been facing -- Cueto having been preceded by Detroit's high-caliber rotation -- Hurdle acknowledged that the Pirates have totaled seven mere runs in their last four games, winning three of them by the graces of sensational pitching.
"We've got more offense in this lineup. We're all aware of that," Hurdle said. "But I see good things coming."
The skipper must have meant June. It's the month in which his 2012 crew went from icy to boiling. Another June bloom in the offing, starting with Saturday's rematch with the Reds?