"We were one big hit away," Mills said. "When you get those opportunities ... I don't know, maybe guys try to do too much."
The Padres pushed the winning run across in the 10th on an RBI double off the bat of Carlos Quentin to score Chase Headley, who drew a walk against Brandon Lyon (0-2) and stole second base the pitch prior to Quentin's game-winning hit.
The Astros forced extra innings when catcher Jason Castro turned on a 3-1 pitch from Luke Gregerson in the eighth and sent it 371 feet down the right-field line for a homer that tied the game at 7. It was only the second home run of the season for Castro and the fourth of his career.
That was one of 11 hits for the Astros, but one more hit at the ideal time could have turned the night around for Houston.
"Any time you lose by one, you think about how it could have gone differently," said second baseman Brian Bixler, who hit a leadoff homer in the first for Houston. "That's just how it went for us tonight. It's just unfortunate how it ended, but we'll just bounce back tomorrow."
Astros starting pitchers had posted a 1.88 ERA in the team's previous seven games, having not allowed more than two earned runs in any of those contests. Wandy Rodriguez gave up four runs in the second inning, including a two-run double by Nick Hundley, before righting the ship to retire the final 10 batters he faced.
"It took him a while to settle down, and once he got settled down, he was pretty good," Mills said. "Getting to that point, it was too bad it just took him so long. They came out and were very aggressive on him, and the big blow in that second inning was that double by Hundley."
Trailing 5-3, the Astros scored twice in the fourth inning to tie game against Ross Ohlendorf, but they wound up leaving the bases loaded for the third inning in a row. Houston was 0-for-3 with a J.D. Martinez walk with the bases loaded.
"They're one hit away from extending a lead or breaking it open or really getting the momentum on their side," Padres manager Bud Black said. "Ross hung in there. It was a battle for him, no doubt. But he got out of it a little bit."
With Rodriguez mowing down the Padres, the Astros took a 6-5 lead in the sixth inning on a double to right field off the bat of Jed Lowrie that scored Bixler, who had walked and went to second base on a throwing error by reliever Brad Boxberger.
Rodriguez had thrown only 94 pitches and was in a groove when Mills pulled him with two outs in the seventh, saying he didn't want Rodriguez having to face the Padres' right-handed batting order another turn through the lineup.
"He had pitched well and got us back in and allowed us to take the lead and win this thing," Mills said. "Where we were at the lineup, I wanted us to get out of it."
Astros reliever Fernando Rodriguez finished the seventh and then gave up a leadoff walk in the eighth. He was one strike away from getting out of the inning when Jesus Guzman hit a 2-2 pitch that was inches off the ground and lofted into the first couple rows of the Crawford Boxes for a two-run homer to put the Padres ahead, 7-6.
"The home run Guzman hit off of F-Rod was a good pitch," Mills said. "It was down, and he was able to get enough of it to get it over."
Bixler led off the game with a homer for the Astros, and Carlos Lee homered one out later -- his first since May 19 -- to put Houston ahead, 2-0. Bixler, Castro, Martinez and Chris Johnson each had two hits for the Astros, who have scored at least seven runs in three consecutive games.