ANAHEIM (AP) — Mike Trout drove in a run with a double that originally was ruled a homer, Garrett Richards pitched seven strong innings and the Los Angeles Angels beat the Oakland Athletics 4-1 Monday night in the opener of a series between the top two teams in the AL West.

The Angels’ fourth straight victory reduced Oakland’s lead 3 1/2 games, but it did not come without some controversy.

Los Angeles manager Mike Scioscia was ejected by first base umpire Bob Davidson in the fifth inning for arguing after a call was overturned on replay.

Oakland manager Bob Melvin challenged Trout’s towering drive to right field, believing the ball was touched by a fan at the top of the 18-foot wall. Originally ruled a two-run homer, Trout was awarded an RBI double.

Hank Conger had bunted for a hit and continued to second on the first of three throwing errors by third baseman Josh Donaldson — two of which led to unearned runs — ahead of Trout’s hit.

Richards (6-2) allowed a run and four hits, struck out four and walked none.  The right-hander, who pitched four-hit ball through eight innings last Wednesday in a 4-0 win at Houston, gave up just two harmless singles over his final 5 1/3 innings against an offense that came in leading the majors in runs and on-base percentage.

Joe Smith pitched a perfect eighth inning and Ernesto Frieri struck out the side in the ninth for his 11th save.

Jesse Chavez (5-4) allowed three runs — two earned — and eight hits in six innings and struck out five. It was the ninth time in the right-hander’s 13 starts this season that he yielded fewer than three earned runs, but his record in those games is only 4-2.

The Angels, coming off sweep of the Chicago White Sox, were out to avenge a three-game sweep by the Athletics 1 1/2 weeks earlier at Oakland. They broke a 1-all tie in the fourth with a bloop RBI single by Raul Ibanez. Ibanez’s hit drove in David Freese, who drew a leadoff walk after walking all four times up in Sunday’s game.

Stephen Vogt and Yoenis Cespedes each had two hits against Richards, who was 0-3 with a 7.50 ERA in his six previous career starts against the A’s. Vogt opened the scoring in the second inning with a two-out RBI single after a double by Cespedes.

Chavez hit Conger on the right elbow with his first pitch of the third, after Richards plunked John Jaso on the left foot with two out and the bases empty in the top half.

Conger hustled to third on Kole Calhoun’s bloop single to left-center and scored the tying run on a sacrifice fly by Trout, who was robbed of extra bases on a leaping catch by center fielder Coco Crisp a few feet in front of the fence. Conger added an RBI single in the eighth against Jim Johnson.

Scioscia said before the game that Tuesday night’s scheduled starter, Tyler Skaggs, will go on the 15-day disabled list because of a right hamstring strain. Hector Santiago was expected to be recalled from Triple-A Salt Lake to make the start.

NOTES: Scioscia’s ejection was his first this season and 37th since becomming Angels manager in 2000. ... The Athletics’ failed to hit a home run after getting at least one in each of their previous 16 games (27 total). ... Richards’ next start will be in Atlanta next weekend. He has allowed no more than two runs or five hits in any of his six road starts this season. ... Oakland 1B Alberto Callaspo, whom the A’s acquired from the Angels in July 2013, was 0 for 3 is hitless in 13 career at-bats against Richards.