Dominguez hit a three-run homer, Tyler Greene added a solo shot and the Astros slowed Cincinnati's run to the NL Central title with a 5-1 win over the Reds on Sunday.
The 23-year old former first-round pick of the Marlins came to the Astros in exchange for Carlos Lee. All three of his homers have been at the expense of the Reds, and the last two were key in winning two games in this series. He hit a ninth-inning, three-run home run off Aroldis Chapman on Friday to lift the Astros to a 5-3 win.
"I'm really pleased with the guys," said Astros interim manager Tony DeFrancesco, who like most of his players wasn't here to endure Houston's struggles on the road. "It's been a long season for a lot of these guys. To win a series against the team with the (second-best) record in baseball is great. Dominguez had the big hit."
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.
Gonzalez developed a blister on his right foot and had to leave the game against his wishes.
"He's had two good outings. He was landing at the same spot that Cueto was. His foot was irritated. They (trainers) tried to fix it but couldn't. He should be fine for his next start."
Gonzalez's career was in a downward spiral until he landed with the Astros. He was released twice by major league teams and went to the Mexican League before Houston signed him to a minor league deal in August.
He wanted to ignore the blister and continue.
"I told Tony D, that I'm Mexican and we are all in, all the time," Gonzalez said. "He told me that it was enough. I'm feeling good. I didn't expect two wins but I'm more mature now. I'm doing a lot of work in the gym and outside."
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.
After going 11-0 in his first 13 afternoon starts this season, Johnny Cueto has struggled in his last two. He 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.
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.
"It was changeup or cutter in the middle of the plate but it didn't do much," Dominguez said. "I feel good and relaxed. I'm getting good pitches to hit and getting the barrel on the ball. Hitting home runs of two of the best pitchers in the game will boost my confidence for the rest of the season."
Cueto (17-8) matched his season low in innings while losing a second consecutive start for the first time since July 3.
"It was a hard day, just a tough day. I threw the pitches that I wanted to. It was just one of those days," Cueto said through an interpreter.
"Johnny was just getting the ball up," manager Dusty Baker said. "We didn't get a lot of offense against Gonzalez. He did a good job of mixing up his changeup and fastball."
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.
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.