Tuesday's night's game was halted because of heavy rain, and soon snow, after Reds reliever Lucas Sims walked in a run to give the Diamondbacks a 5-4 lead in the eighth.
The restart Wednesday was delayed 25 minutes because of a band of heavy snow that passed through before the sun came out.
Sims then pitched out of a bases-loaded jam. But Cincinnati was shut out in its last two chances.
Jesse Winker singled with one out in the ninth, but Tyler Naquin popped out and Eugenio Suarez struck out swinging.
On Tuesday night, pitching in a driving rain, Sims hit pinch-hitter Wyatt Mathisen to load the bases and then walked Carson Kelly on a full count before the game was stopped.
Andrew Young, who had entered as a defensive replacement in the seventh, led off the eighth with a tying homer to center field against Reds reliever Tejay Antone.
Kyle Farmer put Cincinnati in front with a two-run homer in the sixth off Yoan Lopez, who entered after Zac Gallen walked Tucker Barnhart with two outs.
Arizona scored three times in the first on three singles and an errant throw by second baseman Jonathan India on a potential double-play ball.
J.B. Bukauskas (1-0) got the third out in the seventh for the win in his major league debut. Amir Garrett (0-1) took the loss.
''It was kind of unconventional, but any time you win a ballgame you just take it how it is,'' the 24-year-old Bukauskas said. ''It's a cool story for sure.''
ABOUT THAT SUSPENSION
Sims said Tuesday's wet and cold game should have been suspended before he plunked Mathisen.
''I thought there was a lot of safety issues. ... I don't know when the last time I've hit a right-hander with a slider,'' Sims said. ''Yeah, I was concerned.''
Sims went into manager David Bell's office Tuesday night to tell him he wanted to finish the eighth and work out of the jam.
Reds third baseman Mike Moustakas is out because of a viral illness that is not COVID-19-related. He was placed on the 10-day injured list retroactive to Saturday.
The Reds planned to send right-hander Tyler Mahle (1-1) to the mound to face Diamondbacks right-hander Merrill Kelly (1-2) in the nightcap. Kelly earned a win despite allowing six runs in six innings against the Nationals on Thursday. He has allowed 23 hits and 15 earned runs in 16 innings this season. Mahle yielded two runs in five innings in a loss to the Giants on Wednesday.
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