SAN DIEGO -- Hitting for power was one of the goals that Yonder Alonso set for himself this season. So far, the San Diego first baseman is making some good strides.
Alonso homered and the Padres continued their recent dominance of the Arizona Diamondbacks with a 7-6 victory before an announced crowd of 31,223 on Friday night at Petco Park.
Alonso tagged Arizona starter Wade Miley for a two-run homer with two outs in the fifth inning that gave the Padres a 4-3 lead, one they would never surrender.
It was Alonso's fourth home run of the season, tops for San Diego, and almost half of what he hit last season.
"It was definitely one of my concerns during the offseason," he said of his lack of power, managing just nine home runs in 549 at-bats last year. "How could I make myself a better hitter? Not only getting on base, but if you get a ball that might just reach the warning track ... fix it and make an adjustment. For me, it was just to correct those things, and so far it's paying off."
Alonso said he had trouble with Miley's fastballs early on but adjusted to it.
"He's got a good fastball," Alonso said. "I got a fastball kind of elevated, middle in. He got me to foul off some pitches obviously inside. I wasn't catching up to it. So I just made a little adjustment."
The win was San Diego's 10th in 13 games over the Diamondbacks (15-14) and its 15th in the past 23. It also extended Arizona's losing streak to four.
The Padres (12-17) led 7-3 with two outs in the ninth when Huston Street gave up a three-run homer to Gerardo Parra. But Street got Martin Prado to fly out to right to secure the outcome and his seventh save.
Jason Marquis (3-2) had another erratic outing but maintained enough control for the victory. Marquis allowed three runs and four hits, striking out five and walking five in six innings.
"Tonight's probably the best I've felt all year as far as my delivery," Marquis said. "Physically, I feel the same but sometimes the timing doesn't allow you to attack the zone. Obviously, the ball was up a little bit tonight. But with my team down 3-2, they helped me out with some double plays and put some timely runs on the board."
The Padres added a run in the seventh on an RBI single by Kyle Blanks and two in the eighth on a sacrifice by Everth Cabrera and a run-scoring double by Chase Headley, who extended his hitting streak to eight games. Headley's RBI turned out to be the difference.
"I should have walked Headley instead of trying to pitch around him," Arizona manager Kirk Gibson said. "That was my mistake."
Second baseman Jedd Gyorko had a career-high three hits for the Padres, who have won seven of their last nine.
Miley (2-1), who had gone at least six innings in his previous four starts, lasted five, allowing four runs and nine hits. He walked three and struck out four.
"I was battling a bit," Miley said. "You don't always feel your best every time. But I had some opportunities to get out of it."
Miguel Montero led off the second with a home run, driving Marquis' 1-0 pitch over the center-field wall for a 1-0 Arizona lead.
The Padres took a 2-1 lead in the bottom of the inning when Chris Denorfia drove in Gyorko with a single to center, then Denorfia scored on Cabrera's triple to right center with two outs.
Arizona regained the lead with two runs in the fourth on a run-scoring double by Eric Chavez and an RBI groundout by Cliff Pennington.
NOTES: Headley reaffirmed his decision not to negotiate a new contract during the season. Any new deal with the Padres would have to occur during the off-season, Headley told a group of reporters before the game. Headley's comments come on the heels of Padres executive chairman Ron Fowler saying earlier this week the club wanted to make the third baseman its highest paid player, though no negotiations had taken place. ... Padres left fielder Carlos Quentin was scratched from the lineup because of a sore right knee and replaced by Jesus Guzman. Quentin pinch hit in the eighth and struck out looking. Jesus Guzman replaced Quentin in Friday's lineup. ... Twenty of the Diamondbacks' 28 previous games have been decided by two runs or less. They also were the only major league team to avoid being shut out entering Friday's game.