Cain gave up just one hit from the mound, striking out 12 and not conceding a walk. His only blemish came via opposing pitcher James McDonald's single in the sixth inning.

Aubrey Huff spearheaded the Giants' offence with two hits and three RBI, including a two-run homer.

Meanwhile, World Series winners St Louis were beaten 9-5 in their first home game of the new campaign.

The Cardinals crashed 9-5 to the Chicago Cubs at Busch Stadium.

There were other notable occasions in the MLB on Friday.

Gaby Sanchez's walk-off double gave the Miami Marlins a 5-4 win over the Houston Astros, their first victory in their new ballpark.

Anniversary

And Josh Beckett pitched eight innings of one-run ball as the Boston Red Sox began the celebrations for the 100th anniversary of Fenway Park with a 12-2 win over the Tampa Bay Rays.

Meanwhile, the Atlanta Braves also won their home opener, beating the Milwaukee Brewers 10-8 thanks to home runs from Brian McCann and Matt Diaz.

Cincinnati Reds closer Sean Marshall gave up a bases-loaded single to Jayson Werth to hand the Washington Nationals a 2-1 win in the 13th inning, while Alex Rodriguez hit his 630th home run as the New York Yankees beat the Los Angeles Angels 5-0.

Ian Kinsler homered in the Texas Rangers' 4-1 win over the Minnesota Twins and the Cleveland Indians overcame the Kansas City Royals 8-3.

Bartolo Colon pitched seven shut-out innings in the Oakland Athletics' 4-0 victory over the Seattle Mariners, while the Los Angeles Dodgers beat the San Diego Padres 9-8.

The New York Mets beat the Philadelphia Phillies 5-2, the Colorado Rockies were 7-6 winners over the Arizona Diamondbacks, the Chicago White Sox saw off the Detroit Tigers 5-2 and the Toronto Blue Jays slipped up 7-5 against the Baltimore Orioles.