The Padres surprised Arizona for the second straight night, winning 3-1 on Saturday as Wade LeBlanc and three relievers combined on a five-hitter and Orlando Hudson and Jeremy Hermida hit solo homers.
The Diamondbacks' lead in the NL West was trimmed to five games over the defending World Series champion San Francisco Giants, who won 6-5 at Colorado. Each team has 10 games to play. The Diamondbacks' magic number for clinching the division remained at six, meaning any combination of Diamondbacks wins and Giants losses totaling six will give Arizona the title.
Arizona also was held to five hits in a 2-0 loss to the Padres on Friday night.
"I think we're trying a little too hard probably," said catcher Miguel Montero, who had two doubles off LeBlanc. "The team seems good. It's still looking good. We've just got to play a little better baseball. We've got to come back tomorrow and do a little better."
Arizona lost its third straight game, its longest losing streak since dropping six from Aug. 17-22.
"We've been through these streaks before," manager Kirk Gibson said. "Nobody likes them. We fixed them before. We need to get after it. It's disappointing. But we have nobody to blame but ourselves -- and we're the people who can fix it as well and we will."
With the score tied at 1, Hudson homered onto the top of the out-of-town scoreboard on the right-field wall with two outs in the fourth, his seventh. It came on a full-count pitch from Josh Collmenter (9-10).
Hermida led off the seventh with a homer into the seats in right-center, one of the deepest parts of Petco Park. It was his second.
LeBlanc's only mistake was allowing Aaron Hill's solo shot to left-center on a full-count pitch with one out in the first, his second.
San Diego tied it in the second when Hudson hit a two-out single to right, advanced when Hermida was hit by a pitch and scored on Andy Parrino's single.
LeBlanc (4-5) allowed four hits, struck out four and walked three. Relievers Luke Gregerson and Chad Qualls each threw a scoreless inning before All-Star Heath Bell pitched the ninth for his 39th save in 44 chances. Bell struck out Justin Upton looking and got Miguel Montero to fly out to left before allowing a single to Paul Goldschmidt and walking Chris Young on four pitches. Bell ended it by throwing a called third strike past pinch-hitter Lyle Overbay on a full-count pitch.
"C.Y. and Overbay got me in Arizona so I wasn't going to give in," Bell said. "I fell behind and made some good pitches off Lyle, right on the corner. C.Y., I didn't make that good pitch, but then again I didn't want him to shoot the ball into right. I wasn't going to give in to those guys. I got Lyle instead of C.Y. I had a base.
"That's kind of our motto, defense and pitching," Bell added. "Good fundamental baseball and good pitching. We're starting to get some good pitching from our starters, and our bullpen's doing what it's supposed to be doing."
Collmenter allowed three runs and eight hits in seven innings, struck out two and walked none.
"I think everyone knows what's going on," Collmenter said. "But we have to win it. We're not here to try to play prevent or something. We want to win this thing going away. We don't want to wait around. Guys know what's going on. Everyone kind of pays attention in their own respect whether it's a lot or a little ... Something like this isn't that big of a problem for us, or a hurdle."
The Padres will wait a few days to determine whether RHP Tim Stauffer makes his next start. He left Friday night's win with tightness in his right arm. ... The series concludes Sunday with Arizona LHP Joe Saunders (11-12, 3.83) facing San Diego RHP Aaron Harang (13-6, 3.85). Harang has gone 4-2 with a 2.62 ERA in his last 10 home starts since May 19. ... Saunders threw his first complete game of the season, and sixth of his career, in a 6-1 win against the Padres on July 26.