Nick Hundley also homered for the Giants, who scored more on Friday than they did in their previous four games combined (five runs).

San Francisco starting pitcher Jeff Samardzija (1-0), coming off the disabled list (strained pectoral muscle) to make his first start of the season, was not particularly sharp but managed to work his way through five scoreless innings to earn the victory.

Mike Trout's eighth-inning home run, his American League-leading seventh of the season, accounted for the Angels' only run of the game.

Hundley's one-out home run in the second inning, his first of the season, got the scoring started for the Giants against Angels starter Andrew Heaney. The game stayed 1-0 until the Giants broke the game open with six runs in the fifth inning for a 7-0 lead.

Hundley led off the fifth with a walk before Williamson hit a two-run homer. Williamson, who had just been called up from Triple-A Sacramento earlier in the day to replace Hunter Pence (sprained thumb), got the start and made an immediate impact. He has six homers this season at Sacramento.

Things only got worse for Heaney and the Angels in the fifth. Back-to-back bunt singles by Gorkys Hernandez and Kelby Tomlinson and a throwing error by Angels first baseman Albert Pujols gave the Giants runners on second and third.

Austin Jackson singled in one run, and one out later, McCutchen hit a three-run homer and the rout was on.

Heaney (0-1) gave up seven runs on six hits and two walks, striking out six and making 76 pitches in 4 1/3 innings.

Meanwhile, Samardzija gave up just two hits but walked four and had to work his way out of a couple of jams.

Twice Samardzija faced Justin Upton in key situations. In the third inning the Angels had runners on first and third with two out, and Upton struck out. Then in the fifth, the Angels had the bases loaded and two out, and Upton flied out to the warning track in left field.

The loss was the Angels' fourth in a row since starting the season 13-3, which matched their best record through 16 games in club history. But in the last four games (three versus Boston and one versus the Giants), the Angels have been outscored 35-4.

--Field Level Media