"The bad thing about it is, I'm running out of time to get arm strength back," said Oswalt, whose ERA rose to 8.57. "I haven't had a lot of luck go my way."
The Padres loaded the bases against Oswalt in the seventh on a leadoff walk to Headley and consecutive singles by Kyle Blanks and Ronny Cedeno.
After a short flyout, Oswalt walked pinch-hitter Guzman on four pitches to force in a run and tie it at 2. Lopez then relieved Oswalt to face Hundley.
The Rockies took a 1-0 lead in the third when Corey Dickerson tripled and Michael Cuddyer doubled.
Colorado added to its lead after Charlie Blackmon reached on a one-out error by shortstop Ronny Cedeno in the fourth and Jordan Pacheco followed with a run-scoring double.
Renee Rivera's sacrifice fly cut the lead to 2-1 in the fifth inning.
NOTES: The Padres swept Colorado at home for the first time since September 2006. ... Rockies C Wilin Rosario was not available because of issues with his wisdom teeth. ... Rockies CF Dexter Fowler (right knee strain) missed his second straight game. ... Despite being swept, Colorado won the season series against San Diego 12-7. ... The Rockies play at San Francisco on Monday night when RHP Jhoulys Chacin (13-8, 3.16 ERA) opposes RHP Tim Lincecum (9-13. 4.50). ... The Padres travel to Philadelphia and will open with RHP Andrew Cashner (8-8, 3.45) against RHP Tyler Cloyd (2-3, 3.57) on Monday night.
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