With the red-hot Pirates and Cardinals both losing, the second-place Reds closed to within one game of first-place Pittsburgh and 1 1/2 games ahead of third-place St. Louis.
Cincinnati came in batting .170 (16-for-94) over its previous three games -- all losses where they scored only one run. It had scored three runs or less in six of the previous eight games.
But the Reds have received tremendous starting pitching. Arroyo's effort was the ninth straight quality start on a 4-5 West Coast road trip with two games remaining. Reds starters haven't allowed a run for the last 22 straight innings, yet things haven't been much fun lately.
"Guys have been going deep in the ballgame and everybody has been kind of really grinding it out," Arroyo said. "It was nice to finally finish one. I think I was the only guy that hadn't finished one all year."
Arroyo, who walked one and struck out eight while throwing 110 pitches, retired the side in order in six of his nine innings.
"You only get one of those games like that every couple of years where everything is just going your way," Arroyo said. "I wasn't having to work too hard. It gave me a chance to settle back in. After the second inning, I didn't think I'd go nine. I was feeling it a little bit from having to go max effort. But they gave me some breathing room and a chance to go deep in the game."
Breathing room? A Reds pitcher hasn't experienced that for a while. And for much of Friday night, the one-run scenario was poised to repeat itself. Wells kept the Reds from getting further ahead as he gave up only five singles in the scoreless second through sixth innings.
"You just can't keep a good team down forever like that. But when it's 1-0, again, you're like, 'Boys we've got to score some runs,'" Reds manager Dusty Baker said. "The energy was up, the confidence level was up and we just knew that some day we would score some runs."
Leading off the top of the seventh, Todd Frazier walked on four pitches from Wells. Ryan Hanigan followed by smoking a 2-2 pitch into the left-field seats for a two-run homer.
In the eighth, after Jay Bruce led off with a double to left field, there was one out when Frazier took Miles Mikolas deep for a two-run homer to left field and a five-run lead.
The Reds put their leadoff batter on base six times in the game, which led to three of their runs.
"He's kind of been that guy this year for a lot of his starts where we haven't given him too much run support," Hanigan said of Arroyo. "He's been pitching well, really, all year. His win-loss record should be a lot better if we gave him some run support."
With a lead for the entire outing and spacious Petco Park as a backdrop, Arroyo could throw whatever he wanted, whenever he wanted.
"All his breaking stuff and his changeup are different speeds, so it's just tough to make the adjustments," Padres center fielder Will Venable said. "That's just what he does. He had a great feel for everything tonight and made all the pitches he needed to make."
After a Venable single in the fifth that put runners on first and second with one out, Arroyo retired 13 in a row until a two-out single by Chase Headley in the ninth. Two drives -- from Mark Kotsay and Carlos Quentin -- reached the warning track.
"It's definitely nice to have that cushion to be able to go out there hard and say, 'If you're going to hit it out of the ball 400 feet to the opposite field, go ahead,'" said Arroyo, who is 4-5 with a 3.73 ERA this season.
However, Arroyo came in getting only 3.5 runs per game over his previous 16 starts. Friday gave him only his second victory since May 7.
Other Reds pitchers also have been unlucky lately. In Thursday's 2-1 loss to San Diego, Mat Latos pitched seven scoreless innings and came up empty before San Diego won in walk-off fashion. On Wednesday, Mike Leake gave up three first-inning runs and nothing else but lost a 4-1 game to the Dodgers.
"We've been struggling to put runs on the board," Cozart said. "It's got to be tough as a pitcher -- they've got to think 'If I give up a run, we might lose,' or stuff like that."
This time, there were no such worries by the end of a Friday evening in San Diego.