(AP) -- San Francisco's No. 5 starter Ryan Vogelsong has a tough act to follow. That is, he has a couple of tough acts to follow.
The Giants' rotation has yet to allow an earned run, and Vogelsong will try to keep that impressive streak intact when he takes the ball Saturday against the St. Louis Cardinals.
San Francisco's formidable rotation is off to a stellar start, as Matt Cain, Madison Bumgarner, Tim Lincecum and Barry Zito have combined to give up two unearned runs and 12 hits over 26 innings.
"Unbelievable," manager Bruce Bochy said after Zito limited St. Louis to three hits over seven innings in a 1-0 win in Friday's home opener. "We know that's amazing and we can't expect that."
The last team to open a season with such a streak was the 1976 Milwaukee Brewers, which saw its starters go 31 2-3 innings before giving up an earned run.
Friday's victory marked the Giants' fourth straight over the Cardinals - a streak that started with San Francisco facing elimination down 3-1 in last season's NL championship series. The Giants rallied for an improbable NL pennant, then swept Detroit to win the World Series - a title celebrated throughout the home opener.
Vogelsong was clutch in the NLCS, giving up a run and four hits in seven innings in each of his two starts, winning Games 2 and 6. The right-hander also shut out the Cardinals over seven innings in his lone regular-season start against them in 2012.
Although he's rounding out San Francisco's rotation, Vogelsong is hardly a back-end starter. An All-Star in 2011, he pitched for Team USA in the World Baseball Classic after going 14-9 with a 3.37 ERA last season.
While San Francisco's pitching already seems to be in mid-season form, the offense is off to a slow start.
The Giants (3-1) have scored nine runs with three extra-base hits, and they left 11 runners on base Friday. The lone run scored when Jake Westbrook walked Angel Pagan with the bases loaded in the fourth inning.
Cleanup hitter Buster Posey, the 2012 NL MVP, is batting .231 without an RBI and No. 2 hitter Marco Scutaro, the NLCS MVP, is 1 for 15.
The Cardinals (1-3) were just as stagnant Friday, mustering three hits after combining for 15 runs and 26 hits in their previous two games. They've totaled two runs in losing their last four games in San Francisco, which includes the playoffs.
"Same guy we saw last year," manager Mike Matheny said of Zito, who also shut down the Cardinals in Game 5 of the NLCS.
Matt Holliday, 0 for 3 in the series opener, has routinely struggled at AT&T Park, batting .200 in seven regular-season games there since 2010 - his lowest at any ballpark. He is 2 for 8 lifetime against Vogelsong.
Yadier Molina, who was hitless in nine at-bats against Vogelsong last season, will likely be behind the plate to catch Shelby Miller.
Miller, who made his major league debut as a September call-up last season and went 1-0 with a 1.32 ERA, earned the fifth spot in the rotation after going 2-0 with a 3.94 ERA in five Grapefruit League games - two starts.
The righty had five relief appearances in 2012 before making his first start in the regular-season finale, yielding a hit over six shutout innings against Cincinnati. He made St. Louis' postseason roster and pitched out of the bullpen in Games 2 and 6 of the NLCS, allowing two runs and four hits over 3 1-3 innings.
