Johnny Cueto spent the first five months of the season as Cincinnati's "Mr. Sunshine."

Now? Bring on the night.

Cueto, the Reds' Cy Young Award candidate who was perfect through his first 13 afternoon starts, suffered his second straight loss under the sun, falling 5-1 to the last-place Houston Astros on Sunday.

"It was a hard day — just a tough day," Cueto said through an interpreter. "I threw the pitches I wanted to. It was just one of those days."

Matt Dominguez hit a three-run homer, Tyler Greene added a solo shot and Houston slowed Cincinnati's run to the NL Central title.

Edgar Gonzalez allowed two hits and one run in five innings against the Reds, who came in with a magic number of 14 for eliminating second-place St. Louis. Gonzalez (2-0) walked one and struck out six, and the Astros limited Cincinnati to five hits overall while winning a road series for the first time since early June against the White Sox.

The Reds, who also lost two of three against Philadelphia in the first series of their nine-game homestand, have lost back-to-back series for the first time since being swept by Cleveland June 18-20 and losing two of three to Minnesota June 22-24.

Houston relievers Wesley Wright, Mickey Storey and Wilton Lopez combined for eight strikeouts over four shutout innings.

After going 11-0 in his first 13 daytime starts this season, Cueto gave up eight hits and four runs in seven innings of a 4-2 loss to Philadelphia on Labor Day and followed up by getting knocked around for four runs on nine hits with six strikeouts in four innings on Sunday. His main problem was location, manager Dusty Baker said.

"He was throwing the ball well," Baker said. "He had good stuff. He was just getting the ball up. He threw a high changeup to Dominguez."

Cueto (17-8), who already had a single-season career-high with 188 2-3 innings going into the game, matched his season low in innings while losing a second consecutive start for the first time since July. He insisted fatigue wasn't an issue.

"I'm working hard," he said. "We're all working hard. I have three more outings. I'm just going to try to keep working hard."

The last-place Astros scored a first-inning run for the third time in the three-game series. Jimmy Paredes, Brian Bogusevic and Brett Wallace each singled to load the bases with nobody out, setting up Fernando Martinez's sacrifice fly.

Houston took command with a two-out, fourth-inning rally sparked by Wallace's single to right. After Martinez walked, Dominguez drove Cueto's 1-0 pitch 368 feet into the left field seats for his third home run of the season and second three-run shot of the series against one of Cincinnati's more dominant pitchers. Dominguez's three-run homer off Aroldis Chapman on Friday gave Houston a 5-3 win.

Catcher Ryan Hanigan credited Houston's opportunistic young hitter.

"It's just baseball," he said. "The mistakes he made weren't getting missed. That happens. He wasn't as sharp as he wanted to be."

The Reds got on the board in the fourth. Joey Votto walked with one out and scored on Jay Bruce's triple to center field. The Astros got that run back on Green's 10th homer of the season, a 378-foot shot into the right field seats off of Tony Cingrani with one out in the sixth inning.

"We didn't get a lot of offense against Gonzalez," Baker said. "He did a good job mixing up his changeup and fastball."

Notes: Gonzalez left the game with what was described as a "minor injury to his right foot." ... The Reds reported that RF Jay Bruce is the first player in major league history to hit at least 20 home runs as a rookie and then improve on that total in each of his next four seasons. ... The Astros finished 399-439-1 against the Reds in 51 seasons in the National League. Houston shifts to the AL West next season. ... Houston manager Tony DeFrancesco is hoping SS Jed Lowrie can rejoin the team in Houston after being out since July 15 with injuries to his right ankle and leg. Lowrie was 0-for-4 with two RBIs as the designated hitter for Single-A Lancaster on Saturday in the first game of a playoff series with Hudson Valley.