"Pretty exciting," D-backs manager Bob Melvin deadpanned to reporters after the game.
The D-backs carried a 7-3 lead into the ninth, and with closer Brandon Lyon needing the work -- he hadn't pitched in a week -- Melvin brought him in even though it wasn't a save situation.
"I don't think he's the kind of guy where you have to bring him into a save situation," Melvin said. "I don't think he's the kind of guy that needs the emotion or the adrenaline."
Whether it was the lack of urgency or simply rust, Lyon struggled to hit his spots with his fastball and what was not a save situation suddenly turned into one.
The Padres loaded the bases with one out, and Adrian Gonzalez came through with a two-run single to center that almost proved disastrous as the ball nearly skipped by Chris Young.
Chase Headley followed with a single to right that scored Kevin Kouzmanoff, and suddenly the Padres were within a run.
Melvin then turned to Tony Pena, and the right-hander got Nick Hundley to ground into a fielder's choice before Luis Rodriguez flied out to center to end the game.
It was Pena's second save of the year and another in a string of good performances after tweaking his mechanics to avoid having his front shoulder fly open.
"I came in and threw strikes," Pena said.
That was something that Padres starter Josh Banks struggled with in the first inning. The right-hander walked the first two batters of the inning and three of the first four, as the D-backs gave their starter, Doug Davis, a 4-0 lead.
"The team going out there and scoring four runs made it a lot easier to go out there and throw strikes," Davis said.
Still, Davis, who had scuffled with his command in his previous three starts, didn't look sharp in the top of the second as he gave two of the runs right back. The lefty was able to settle in after that and wound up going six innings.
"Walking only two compared to my last three starts, that's huge," he said. "I ended up getting strike one a few more times tonight, and I was able to make them hit my pitch."
Dunn gave the D-backs some breathing room in the fourth with a two-out, two-run homer. It was his first since coming over in the Aug. 11 trade from the Reds and his 33rd of the year.
"He's been grinding, trying to get that home run," Melvin said.
That's because not only was Dunn trying to make a good impression in his first home game since the trade, but he was also in the midst of a 60 at-bat homerless streak, almost unheard of for him.
"I was grinding because I hadn't hit one," he said. "It's been a long time since I've hit a homer, and that's not really not like me. I'm usually walking and hitting balls out of the park."
The win, along with the Dodgers' loss to the Rockies, moved the D-backs one game up in the National League West.
The adrenaline and excitement of a pennant race is something new to Dunn, but as he discovered in his first game for Arizona last week against the Rockies, it's one he likes.
"It was kind of nerve-wracking, but I settled down a lot quicker than I did in Colorado," Dunn said of his home debut. "That's such a good feeling. That's not a feeling that I've been getting very often besides maybe Opening Day and opening day of deer season."