The Reds ambushed Milwaukee starting pitcher Wily Peralta in the first inning.
Eugenio Suarez drew a one-out walk but the Reds got successive singles from Adam Duvall, Brandon Phillips, Scott Schebler and Tyler Holt with two outs to post a three-run inning.
Emergency starter Keyvius Sampson nursed the lead for 4 2/3 innings when he ran out of gas but left leading 3-0. Sampson pitched to give Anthony DeSclafani an extra day. Sampson walked Ryan Braun to load the bases with two out in the sixth. Blake Wood retired Hernan Perez on a routine fly to left to protect the lead.
"I'm happy for the guys that have been here the bulk of the season. Early in the season when we were struggling, we asked guys to take on roles they weren't prepared for. We plugged in pitchers that weren't ready to be here. We went through a lot of growing pains," Bryan Price said. "It's nice to have some of the guys that tasted real struggles bounce back and see success for the work they put in on their craft."
Sampson was one out short of the win. Wood's record improved to 6-3 with 1 1/3 scoreless innings.
"With the bases loaded and Perez coming in, another guy having a nice year, it was time for Woody to come in and clean it up," Price said. "Keyvius didn't get the win but I'm really happy for him. He didn't get the win but he gave us a huge boost."
Sampson has been up and down all year but has given the Reds big efforts when called upon.
'As far as not getting five innings in to get the W but this was pretty good. I hate having two walks but they happen. Honestly, I just wanted to give the team everything I had. I tried to keep them in the game," Sampson said. 'I was more tired. When you get tired you try to aim the ball. My arm lagged behind."
"Keyvius is one of the guys who had options," Price said. "When we needed a roster spot for a position player, he was the one we sent down. He went to Louisville and pitched better. Keyvius didn't do anything to pitch himself off the team but he handled it and got better."
Sampson is seizing this late season opportunity to get better and earn a larger role next season in whichever role he has.
I'm just trying to finish the season strong," Sampson said. "Whether I'm starting or relieving I just want to be a bigger part of the team next year. 'It's been tough going up and down to the minor leagues but I'm not the first guy to do it and won't be the last. I'm trying to keep a positive mindset."
Sampson and his teammates are much better than they were in April and May.
"The improvement for me has just been trusting my stuff. For the team it is relying on each other. Like tonight with bases loaded Woody comes in behind me to clean it up for me. It is trusting that if I give it all I have the guy behind me is going to pick me up," Sampson said.
Peralta settled in and retired15 batters in a row until Brandon Phillips beat out a slow roller to thirdbase.
Michael Lorenzen entered in the seventh inning.
Jonathan Villar forced pinch hitter Jake Elmore, who singled batting for Peralta. Villar went to second on a balk but was thrown out at home by Steve Selsky on a single by Scooter Gennett to end the seventh.
Selsky came in for Holt on a double switch with Schebler moving to center.
"It was a big play," Price said. "Steve hasn't gotten in a lot of games since being called up. It was huge to get us out of the inning with (Ryan) Braun coming up."
Raisel Iglesias started the eighth for the Reds.and pitched two scoreless innings for his third save.