It was left to the great Vladimir Guerrero to decide it with one majestic stroke. Harden and the Rangers prevailed, 2-1, on Guerrero's two-run homer, pushing the Angels a daunting nine games back in the American League West chase.
"Not too many people can hit that pitch," Angels catcher Mike Napoli said of Guerrero's fourth-inning blast to left-center on a Haren fastball that was down but caught too much of home plate. "He's been doing it forever. He's got that eye-hand coordination and gets bat to ball. I saw it for a long time from him.
"It wasn't a bad pitch. Vladdy hits bad pitches."
Howard Kendrick also homered, in the seventh against Harden, who worked out of trouble in the inning and watched Frank Francisco and Neftali Feliz get the final six outs. The save was No. 29 for Feliz, the young All-Star who anchors a superb Texas bullpen.
"Those guys have the heart of a champion over there," gracious Rangers manager Ron Washington said, "and we're growing one. It seems like it's a special game every time we play."
Going the distance, Haren yielded just five hits and two walks, hitting one batter. His six strikeouts give him 155 for the season, matching teammate Jered Weaver.
"Danny Haren pitched his heart out," Angels manager Mike Scioscia said. "Both those guys pitched well. Harden was in the zone a lot, throwing strikes. We really couldn't get any momentum going on the offensive side."
Coming off a nine-run eruption in the series opener, the Angels were scuffling again offensively when Kendrick sent a laser over the center-field wall in the seventh inning, his eighth homer cutting the deficit in half.
But Harden escaped further trouble after Napoli's two-out double and hitting Erick Aybar with a pitch, retiring Maicer Izturis on a grounder to graceful Elvis Andrus at shortstop.
Haren breezed through three innings while yielding a single and a hit batsman.
The three-time All-Star walked David Murphy leading off the fourth before Guerrero lifted the first pitch he saw over the wall in left-center, in excess of 400 feet, for his 21st homer of the season.
"More than anything, I was able to do it on my son's fourth birthday," Guerrero said. "That means more to me than doing it against the Angels."
He'd been homerless in 68 at-bats, going back to July 9.
"You go through those stretches where you're not feeling as good or swinging as good," Guerrero said. "This was one of those stretches, but tonight I was able to pick it back up."
Haren wishes he'd waited a little while longer.
"I'm trying to go in," Haren said, unhappy with the location of the pitch. "I know it's down, and usually it's safe down. Although it was down, I was trying to go in. I wish I had that pitch back. It cost us a game."
Haren, acquired last Sunday from Arizona for Joe Saunders and three prospects, had been knocked out of his Angels debut by a line drive off the bat of Boston's Kevin Youkilis with two outs in the fifth inning.
This time, with precision and economy, Haren delivered 27 outs on 119 pitches but didn't get the brand of offensive support he needed.
"It was a great atmosphere," Haren said. "I kind of had a feeling after last night's crazy game [a 9-7 Angels comeback victory] it was going to be like this.
"I feel better about this one than the last one. But it was a big game, and I lost. I felt good out there. I'm happy the way I threw. I was in control pretty much the whole night."
Harden, coming off the disabled list for his 14th start as a Ranger and first since June 11, doesn't throw as hard as he once did but he still knows how to get outs.
"He's reinvented himself," Scioscia said. "He used to have that power fastball with a split. He's got a good changeup and a breaking ball he'll make small. Obviously, he's learned to pitch with less velocity."
Harden left Bobby Abreu at second in the fourth after a single and stranded runners at the corners in the fifth, striking out Aybar.
"I played with him for three years," Haren said. "It's been a while since I've seen him. We're both different pitchers now. We used to be power pitchers back then. He's a great competitor. He had it going tonight."
Harden moved to 4-3, while Haren's hard-luck season continued. He's 7-10 overall and 0-2 since coming to the Angels despite giving up only four earned runs in 13 2/3 innings.
"I've always kept up with him and his career," Harden said. "He pitched a great game. It was fun matching up against him."
The Angels, finishing 9-17 in July, send out Weaver against Cliff Lee in Sunday's marquee matchup of aces.
Lyle Spencer is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.