Hamilton hit a two-run homer in the 11th inning, after the Halos rallied to tie it with four runs in the ninth, and they beat the Boston Red Sox 9-7 on Saturday night to snap the AL East-leaders' five-game winning streak.
Brad Hawpe, who came in to play first base in the 10th, singled with one out in the 11th against Craig Breslow (2-2). Hamilton drove the next pitch -- a fastball on the inside part of the plate -- to right-center for his 12th homer and second dramatic blast in three nights.
"I was trying to do a little too much at the plate earlier in the game, and then I understood that I should just be relaxing up there like I've been doing the last couple of weeks," Hamilton said. "I'm just taking it one at-bat at a time and understanding that if you don't success on one, you get to do it three or four more times in the game."
Dane De La Rosa (4-1) earned the victory with a scoreless inning.
It was the third pulsating comeback win at home for the Angels in less than four weeks. On June 20, they turned a 7-0 deficit against Seattle into a 10-9 win, and they rallied with three runs in the ninth against St. Louis on Thursday -- including a two-run homer by Hamilton -- for a 6-5 win.
Boston was leading 7-3 in the seventh when Andrew Bailey relieved injured pitcher Andrew Miller with one out and runners at the corners. He retired Mike Trout on an inning-ending double play with his first pitch.
Bailey then pitched a scoreless eighth before the Angels loaded the bases with two out in the ninth against Alex Wilson.
Red Sox closer Koji Uehara gave up a two-run single to Albert Pujols and an RBI single to Hamilton before Howie Kendrick hit a grounder to third baseman Brandon Snyder. But Snyder's throw to second base sailed into right field, allowing pinch-runner Collin Cowgill to score the tying run.
"I thought I was closer to the base, and my first instinct was to think I could underhand it," Snyder said. "When I looked up, I realized how far I was and Josh was coming down. I didn't know if I was going to make it, so I just rushed and never got a grip. There isn't a worse feeling."
It was Uehara's third blown save in eight chances.
Daniel Nava tied a career high with four hits and scored twice for the Red Sox.
Boston starter Ryan Dempster allowed three runs -- two earned -- and seven hits in 6 1-3 innings. Two of the hits off the right-hander were leadoff home runs by Kendrick in the second and Trout in the third.
"They're a tough lineup and you try to get through it," Dempster said. "As the game went on my slider and split felt a lot better and that helped me out a lot. Everybody (in the rotation) has been throwing the ball really well, so you want to pull your own weight."
Angels starter Jerome Williams gave up five runs -- four earned -- and seven hits in his second start in four days. Williams had a quick turnaround after allowing seven runs, four hits and four walks in 1 2-3 innings of a 12-2 loss Wednesday against St. Louis.
Trout, the only Angels player voted onto the AL All-Star team, put them ahead 3-2 with a shot over the double-decker bullpen in left field for his 14th home run and team-high 56th RBI.
The Red Sox grabbed a 5-3 lead with three runs in the fourth, the first two coming on Jarrod Saltalamacchia's double.
Jacoby Ellsbury singled to center on Williams' second pitch, extending his hitting streak to 16 games.
Chris Iannetta was charged with catcher's interference in the seventh when his glove made contact with Ellsbury's bat. His two errors, plus a fielding miscue in the eighth by Hamilton in right field that led to a Boston run, increased the Angels' season total to 67 and tied Houston for the most in the majors.
"In the ninth inning, I was thinking about that play earlier in the game," Hamilton said of his error. "You think about the situation you put the team in. ... The guys encouraged me to go up there and redeem myself, so you do what you can and what you're capable of to help the team win."
Kendrick's homer was his 11th, three more than he had last season. The eight-year veteran, whose 105 hits are the most by an Angels second baseman before the All-Star break, finished seventh in fan balloting at his position.
- Both teams lined up along the foul lines for the national anthem, followed by a ceremonial first pitch delivered by Donald Yocum. His father, Dr. Lewis Yocum, was the Angels' team physician for 36 years before his death on May 28.
- Trout is the second Angels outfielder to be selected to consecutive All-Star games after beginning his career with the organization. The other is Garret Anderson (2002-03).
- Ortiz, Pedroia and Clay Buchholz also made it onto the All-Star squad from the Red Sox. Buchholz is an All-Star for the second straight year, but he can't play because of a neck strain.
- Ortiz's hit was his 1,682nd as a designated hitter, putting him six behind Harold Baines' record.
- Brock Holt, obtained by the Red Sox from Pittsburgh in December, started at third base and was 0 for 2 with a sacrifice fly in his AL debut. He was recalled from Triple-A Pawtucket on Saturday.