SAN DIEGO (AP) -- The struggling Cincinnati Reds found their way to a road win by beating the majors' career saves leader.
Dunn hit a 3-1 fastball off Hoffman, baseball's all-time save leader with 533, into the right-field seats. The Reds had dropped the first four games of a seven-game West Coast road trip after winning six straight at home.
Dunn's 12th homer of the season was also the 250th of his career.
"Definitely good to get a win," Dunn said. "West Coast games are hard on us. I don't know why, but they are."
Hoffman (0-3) had struggled with two blown saves and two losses in the first three weeks of the season. But he has been sharp lately having allowed only one run in his last nine games since April 13.
"You definitely don't want to walk the leadoff guy in that situation," Hoffman said. "But you still have to try and execute a good pitch at 3-1 with that type of hitter. I got the ball up a little bit and he deposited it."
Dunn hit a drive over the right-field wall an estimated 400 feet.
"The thing with him is you have to try and make him get the ball up," Dunn said. "Everyone knows about his changeup, but he probably gets more people out with his fastball."
San Diego (18-32) has the worst record in the majors and has lost 13 of 19 games. The Padres, who beat Cincinnati 8-2 on Thursday, were trying to win two games in a row for just the fourth time this season.
Cincinnati played without manager Dusty Baker, who was suspended for two games on Friday for his ejection from Thursday night's game for bumping umpire Eric Cooper. Bench coach Chris Speier served as acting manager.
"Dunn picked us up again," Speier said. "We need him. Adam is on one of those streaks that we need from him."
Dunn extended his hitting streak to nine games, during which he has raised his batting average 45 points to .248.
"(Trevor) came in with a fastball to a prolific power hitter and Dunn done got it," Padres manager Bud Black said. "Trevor challenged him and Dunn won the battle."
The game was delayed by rain for 29 minutes in the top of the fifth inning.
Cincinnati's Edinson Volquez was the story before Dunn. The right-hander pitched six innings with a career-high 12 strikeouts. He left with a 2-1 lead after outdueling Shawn Estes. Volquez used a lively fastball, allowing just one run on two hits as his major-league leading ERA rose slightly to 1.34.
Volquez allowed one or no runs for the ninth time in 10 starts.
"I had all my pitches working," Volquez said. "The first inning I threw a lot of pitches, but I got better with each inning."
The only run Volquez allowed came in the fifth inning after a one-out walk to Luke Carlin. Estes laid down a sacrifice and Jody Gerut doubled into the left-field corner for a 1-0 lead.
Volquez struck out the side in each of the first two innings.
Estes matched Volquez through five innings. The left-hander retired the first 11 batters before Ken Griffey Jr. reached on a throwing error by first baseman Adrian Gonzalez in the fourth. Jerry Hairston Jr. got the Reds' first hit with single in the fifth.
Estes allowed two runs on three hits in six innings. He left in the seventh after a leadoff walk to Dunn, a single to Hairston and another walk to Joey Votto loaded the bases with no outs.
Five Reds pitchers combined for 17 strikeouts. ... Kouzmanoff faced Volquez for just the second time in their young careers. The first time proved to be historic when Kouzmanoff played for Cleveland and Volquez pitched for Texas. Kouzmanoff became the only player in major league history to hit a grand slam on the first pitch of his first big league plate appearance. ... Volquez has struck out 10 or more three times this season. ... San Diego hitting coach Wally Joyner sat out the game after he was suspended on Friday for one game following his ejection from Wednesday's game against St. Louis.