Blalock's second homer of the game, a two-run shot with two outs in the ninth inning, gave Texas a 9-7 victory and moved the Rangers within one-half game of the first-place Angels in the AL West.
"If you think one game is more important than another, that means you're not trying to win against a team with a worse record," Blalock said. "You've got to take every game as serious as you can because once it gets later in the year, you start thinking about the games you let slip away."
The Angels rallied from a 7-1 deficit by scoring three runs in both the seventh and ninth. Juan Rivera's three-run homer with two outs in the top of the ninth off Frank Francisco (2-1) tied the game at 7-all
"We didn't get it done in regulation like we wanted to," Rangers manager Ron Washington said. "But the character in that clubhouse showed up."
Blalock, who homered in the fourth, hit the first pitch into the grassy area beyond the fence in center field.
Texas, who took two of three from the Angels in the series, improved to 5-1 against Los Angeles this season. The teams meet again for a three-game set next week in Los Angeles.
"They're owning us right now," Angels center fielder Torii Hunter said. "We're playing good games against them. They just seem coming through with the big hit."
The Angels elected to pitch to Blalock, who had three hits, instead of walking him to face rookie Julio Borbon, who had been called up from the minors Monday.
"I'm smart enough to know that I didn't want to give into him there," Speier said. "I made a mistake. I gave him something way too good to hit with a base open."
Los Angeles completed its comeback against Francisco, who pitched the ninth in a save situation for the first time since coming off the disabled list June 20.
"It was uncharacteristic of Frankie not to close the door," Blalock said. "But when a guy doesn't have his stuff that night, it's up to the offense to pick him up."
Texas starter Kevin Millwood, who went 4-1 with a 1.30 ERA in June, gave up four runs and eight hits in 6 1/3 innings.
Angels starter Jered Weaver allowed seven runs, the most he's given up this season, and eight hits in 5 1/3 innings. The right-hander, who had won five of his last six starts, saw his ERA climb from 2.65 to 3.10.
The Rangers scored five runs in the sixth to take a 7-1 lead.
Borbon batted for Nelson Cruz, who left the game with a stiff lower back, and drove a single to center to put Texas on top 3-1.
Texas added runs on a wild pitch and Chris Davis' grounder. Young and Murphy capped the sixth with consecutive RBI singles that gave the Rangers a six-run lead.
Chone Figgins had an RBI triple and Hunter added a two-run double that made it 7-4 in the seventh.
The inning was cut short when Guerrero was caught stealing second, one of four times an Angels runner was thrown out on the bases.
"It was one of those games where we didn't do a lot right," Weaver said. "We gave that game away."
Rangers CF Josh Hamilton went 1-for-7 as the DH on Wednesday night for Triple-A Oklahoma City in his minor league rehab assignment. Hamilton, recovering from abdominal surgery, will likely play the field for Oklahoma City Thursday and Friday. If all goes well, he could be activated over the weekend. ... Angels manager Mike Scioscia said he's still planning on activating RHP Ervin Santana for a weekend start against Baltimore, with Friday night the probable target date. Santana has been out since June 12 with right forearm stiffness. ... The Nick Adenhart Memorial Fund made a $5,000 donation to Halfway, Md., Little League on Wednesday. It was the first donation from the charitable fund named for the Angels pitcher who was killed in a car accident April 9.