A lack of timely hitting and an awful inning out of the bullpen spoiled a strong outing by Arizona's young Daniel Hudson.
It was a familiar story for the Diamondbacks after two straight seasons in the NL West basement.
Bronson Arroyo gave up just one run — unearned on his own throwing error — and the Reds beat the Diamondbacks 6-1 on Saturday night.
Arroyo (2-0) scattered eight hits as the Diamondbacks failed to convert two scoring threats in the first four innings, then Arizona reliever Juan Gutierrez's throwing error cleared the way for the Reds' four-run ninth.
"We made some mistakes in the last inning and that ultimately really cost us," Diamondbacks manager Kirk Gibson said.
Hudson (0-2) gave up two runs on three hits in seven innings, striking out eight and walking three. After scoring twice in the first inning, the Reds had only two baserunners in the next six against the 24-year-old right-hander, and neither got past first base.
"I battled my command in the first inning," he said. "I was throwing a little too much across my body and left a couple of pitches up. I didn't have good command in the first but other than that I felt good."
Scott Rolen, who had an RBI single off Hudson in the first, wasn't surprised by the performance.
"We've faced him three times and he's thrown the ball well every time," Rolen said. "The ball just explodes out of his hand."
Jay Bruce brought in the second run with a sacrifice fly for the Reds in the first.
Arizona cut it to 2-1 in the sixth when Chris Young singled, advanced from first to third on Arroyo's throwing error, then scored on Melvin Mora's two-out single.
After Cincinnati's Aroldis Chapman hit 103 mph on the Chase Field radar gun while throwing a scoreless eighth, the Diamondbacks fell apart in the ninth.
Gutierrez walked the leadoff batter, Joey Votto, and then tried to barehand Rolen's grounder. He knocked the ball down, grabbed it, then threw it away to first. Instead of what could have been a double play had the ball made it past the pitcher to an infielder, runners were at second and third with no outs.
Jonny Gomes doubled off the glove of Mora at third to bring both runners home.
Gomes called taking advantage of an opponent's mistake "the name of the game."
"You look at the end of the season and the more times you do that, the chances are more times you're just flat-out winning ballgames. If they're going to give you extra outs, that's what you've got to do is capitalize on them," he said.
Hudson struck out Drew Stubbs to start the game, then Brandon Phillips singled and Votto walked. Rolen followed with a single for his ninth RBI of the season, then Gomes walked to load the bases with one out.
Bruce hit a fly to short center that Young caught and fired toward home. Hudson cut off the throw and relayed it to third to catch Rolen trying to advance. Votto crossed the plate just before Rolen was tagged out to make it 2-0.
In the fourth, Branyan led off with a double off the fence in right but, not particularly fleet, he was held at third on Miguel Montero's single, leaving runners at first and third with one out. Mora popped out, then Gerardo Parra bounced out to end the inning.
"We didn't do a good job with runners in scoring position. We hit 3 for 11," Gibson said. "Two of them we couldn't score on."
NOTES: Votto walked three times. ... Arizona outhit the Reds 9-6. ... Eighteen of the 25 players on Arizona's opening-day roster were not with the team at the start of 2010. ... Ex-Arizona State star RHP Mike Leake (1-0) will make his first appearance against the Diamondbacks when he starts for the Reds in the series finale on Sunday.