Instead of celebrating a three-game sweep, the Diamondbacks tended to closer Chad Qualls, who dislocated his left kneecap on a freak game-ending play.
Qualls immediately motioned to the dugout for help, and trainers and teammates rushed to the mound. After several moments, trainers helped the 6-foot-5, 220-pound Qualls to his feet and off the field.
"It's awful news," Arizona manager A.J. Hinch said. "It certainly doesn't feel good when, instead of shaking hands, your closer's laying on the ground in a lot of pain."
Hinch said Qualls had dislocated his left kneecap but had no other details about the extent of the injury. Qualls underwent X-rays after the game and did not speak to reporters.
It wasn't clear whether Qualls would accompany the Diamondbacks to Los Angeles, where they open a four-game series against the Dodgers on Monday night.
The final play happened so quickly that it appeared Qualls may have been felled by the ball. Hinch learned otherwise as soon as he reached the mound.
"When we got out there, all [Qualls] was saying was, 'It didn't hit me, it didn't hit me. It's my knee," Hinch said.
Hinch said assistant trainer Dave Edwards popped Qualls' knee back into place.
"Now it's a matter of what damage was done," Hinch said.
Qualls got the last four outs for his 24th save in 29 chances, stranding the potential tying run in the eighth and ninth innings.
His injury was a deflating end to an otherwise upbeat weekend for the Diamondbacks, who have won four straight games after losing nine of the previous 10.
Dan Haren (13-8), whose locker is next to Qualls' stall, threw seven sharp innings but wasn't in a mood to celebrate.
"I really don't feel good right now," Haren said. "I know I won the game, we won the game, but he's one of my best friends. To go down like that, especially closing the game for me, it hurts. I feel bad for him and his family."
Haren allowed three runs on six hits and two walks, and he struck out seven.
He outpitched Houston ace Wandy Rodriguez (12-9), who gave up four runs on seven hits and three walks in six-plus innings. Rodriguez struck out seven and allowed multiple runs for only the second time in 11 starts.
Haren worked out of a bases-loaded, one-out jam in the seventh.
"That hurt," Houston manager Cecil Cooper said. "We just couldn't get anything going. I mean, one big swing, and we couldn't get it."
But after singling in the bottom half, Haren spent about 20 minutes on the bases as the Astros made three pitching changes, and it took its toll when he went back to the mound for the eighth and gave up singles to Michaels and Michael Bourn.
With two out, Carlos Lee singled, and Hinch brought in Qualls.
Lee stole second -- his fourth stolen base this season -- and took third on a wild pitch before Qualls struck out Hunter Pence on a pitch a foot off the plate.
The Astros entered August 4½ games off the pace in the NL Central. Sunday's loss dropped them 14 games back of division-leading St. Louis.
"It's definitely a snowball," Blum said. "It seems to be accumulating. We're constantly finding ourselves in situations that we can't get out of."
With a first inning walk, Bourn has reached base in 23 straight games. That matches a career high and is the longest active streak in the majors. Bourn also stole two bases to run his NL-leading total to 48. ... Arizona RF Justin Upton hit his 22nd homer to extend his hit streak to eight games.