"It never gets old -- your first one, your last one, whatever it may be. It's an awesome feeling," Iannetta said.
Pomeranz (1-1) retired David Freese on a grounder to second base and Raul Ibanez on a foul pop to the catcher before Iannetta drove the next pitch to center field and just out of the reach of a leaping Craig Gentry, ending Oakland's four-game winning streak.
"I was just looking for a pitch to hit. It was a fastball over the middle of the plate and I got the barrel to it," Iannetta said. "I know I hit it really well. But Angel Stadium at night, you never know -- and Gentry's a really good outfielder. He almost jumped out of the gym on that one. I think it went off his glove, so I was very thankful that he didn't make an awesome play."
Angels manager Mike Scioscia got six scoreless innings out of his much-maligned bullpen, as the Athletics stranded runners in scoring position in the 10th, 11th and 12th. Joe Smith (1-0), who failed to retire any of the five batters he faced in the eighth inning of the Angels' 10-9 loss on Tuesday night, pitched a scoreless inning for the victory.
"Joe came back from the night before and pitched great. He had life on all of his pitches again," Iannetta said. "It's awesome that he came back and pitched the way he did, along with the rest of the guys. They really stepped up and pitched to their capabilities and just showed what they can do."
Brandon Moss hit a three-run homer for the A's in the fourth inning.
Oakland left-hander Tommy Milone was charged with three runs -- two earned -- and six hits over six-plus innings in his second start and departed with a 4-1 lead. Los Angeles closed to 4-3 in the seventh with a pair of runs after a costly throwing error by first baseman and former Angel Alberto Callaspo, who had never played that position in the majors or the minors until this season.
Dan Otero relieved Milone with two on and none out and Erick Aybar grounded into a force at second. J.B. Shuck followed with a grounder to Callaspo, who tried to start an inning-ending 3-6-3 double play. But his hurried throw couldn't be handled by shortstop Nick Punto and Iannetta scored from third. Albert Pujols added an RBI single one out later.
The Angels put runners at the corners in the ninth with one-out singles by Mike Trout and Pujols, and Trout scored the tying run on a slow fielder's choice grounder to third by Howie Kendrick.
"We went to the ninth inning with the lead, but you put it behind you and move on," manager Bob Melvin said. "We weren't very good defensively tonight."
Callaspo also dropped a relay throw from second baseman Eric Sogard on a potential double-play grounder in the sixth by Freese. But the next batter, Ibanez, grounded into a 4-6-3 DP to end the inning.
The A's snapped a 1-1 tie in the fourth against Tyler Skaggs when Moss drove a 2-1 pitch into the right-field seats with two outs for a three-run homer after Callaspo's RBI double. Skaggs was charged with four runs, seven hits and three walks in six innings.
The Angels will honor the late Jim Fregosi during a two-game interleague series against Philadelphia Aug. 12-13. Fregosi, who died Feb. 14 at age 71, was a six-time All-Star who spent his first 11 big league seasons as an Angels SS and managed them to their first division title in 1979. He also piloted the Phillies to a pennant in 1993. ... This was the first time the Angels played four extra-inning games on the same homestand since June 1975. ... The A's claimed RHP Marcus Walden off waivers from Toronto and optioned him to Triple-A Sacramento. ... The Angels begin a nine-game road trip Friday night at Detroit. Jered Weaver will make his fourth attempt at his first victory of the season, while trying to extend the Halos' winning streak against the Tigers to 10 games.
Copyright by STATS LLC and The Associated Press
ANAHEIM, CA - APRIL 16: Josh Donaldson #20 of the Oakland Athletics reacts after his out at second base during...
37,344 (82.1% full) - % is based on regular season capacity
67 degrees, clear
Home Plate - Tim Timmons, First Base - Todd Tichenor, Second Base - Tim Welke, Third Base - Chris Segal
Brandon Moss is hitting .379 in at-bats ending with a pitch on the outside part of the plate or beyond (his 11 hits are tied for the MLB lead). Tyler Skaggs has the seventh-highest opponent batting average allowed in the majors against outside pitches at .333 (7-for-21).