The Padres saw their lead in the National League West shrink to 4 1/2 over the Rockies, The more immediate concern is the Giants, who pulled within a game after dropping the Dodgers.
Only two other teams have dropped 10 straight games during the regular season and made the playoffs. The slide ties the 1932 Pirates for the longest losing streak by a first-place team.
The 10-game skid is also the longest since the Padres lost a franchise-record 13 consecutive games in May of 1994.
Like many contests during the slump, the Padres weren't able to come up with the types of routine or clutch plays that they had always seemed to have a knack for during the first five months of the season. San Diego committed two errors, one that ultimately led to a run, and could not stage any late magic even after getting the tying run to the plate three times in the ninth inning.
"We're in games," said Padres manger Bud Black. "We're just not generating the big hit, we're not generating the offense to get us over the top. We're just not executing the pitch, making the play that changes the course of a game."
It looked like the Padres (76-59) may have gotten that big momentum play they desperately needed when, after a ground-rule double by Adrian Gonzalez, Miguel Tejada launched an 0-1 pitch from Jorge De La Rosa into left for a two-run homer.
"That was a big hit, it got us tied," Black said. "But you've still got to go out and play three more innings."
It only took one frame for Colorado to regain the advantage for good.
The Rockies (72-64) jumped on the Padres' bullpen for the second consecutive game, as Tim Stauffer (3-3) allowed a broken-bat single to Carlos Gonzalez and a walk to Troy Tulowitzki before Mike Adams gave up the game's biggest blow when, after a double steal, Melvin Mora sent a two-run single to right.
"These kids are tremendous competitors and they have a great understanding of the message," said Rockies manager Jim Tracy. "They're unselfish and they'll execute what you ask them. This is not foreign territory for us. We did a very good job today of taking advantage of what was there for us."
Padres starter Clayton Richard scattered nine hits through six innings, allowing two runs (one earned) with three walks and four strikeouts. He gave up a leadoff home run to Tulowitzki in the fourth that sailed over the wall in center and an unearned run by Ryan Spilborghs in the fifth -- one that crossed the plate partly because of an error in the field by Chris Denorfia followed by a bobbled grounder hit at Chase Headley that may have been have turned into an inning-ending double play.
"I felt all right," Richard said. "Didn't feel great, but didn't feel bad. [Yorvit Torrealba] called a good game, and unfortunately it didn't happen for us."
Either way, it wasn't enough to let Richard play the role of stopper. But the offense hasn't provided much support, either, scoring three runs or less for the eighth time during the skid.
Despite the extended rut, the Padres will still head into Monday's series opener against the Dodgers with a lead in the division. That, Richard said, is plenty of motivation to push through any recent struggles.
"We have a sense of urgency and we understand we have a special opportunity, and we're going to do everything in our control to take advantage of that," he said. "We're looking forward to the task at hand, and it's a real opportunity to show what we're made of and what we're capable of doing."
The Padres moved into first place on April 20 and have been out of the top spot for a total of three days ever since. Black agrees that there still is no reason to go into panic mode just yet.
"Our guys are fine," Black said. "They're playing their [butts] off, but it's just not happening. We're making some mistakes on the mound and in the field that we haven't made before, and we need to rectify that.
"It's in us, because I've seen it. We haven't done it the last 10 games."