The San Francisco Giants are still waiting for the first positive return on their massive investment in starter Matt Cain.

Cain aims to shake off a rough season debut this afternoon in his club's home opener, which comes in the first of three straight against the Pittsburgh Pirates.

A 2002 first-round draft pick, Cain has morphed into one of the top right- handers in the game. He owns a career earned run average of 3.37 in 205 games, going 12-11 in 33 starts last year with an outstanding 2.88 ERA. He also struck out 179 to match the second-highest total of his career.

That earned Cain an extension from the Giants through 2017 that will pay the 27-year-old $127.5 million.

Cain took the mound last Sunday for the first time since inking the deal, but was drilled for five runs on six hits -- including two homers -- on six hits over six innings of a no-decision at Arizona after getting staked to a 6-0 lead.

He'll look to rebound tonight versus the Pirates, who he is 1-2 against with a 3.63 ERA in eight starts.

The Giants return home after beginning the season with a 2-4 road trip. They were swept in Arizona in their first series before taking two of three in Colorado. San Francisco's second victory of the season came on Thursday, a 4-2 win in which 22-year starter Madison Bumgarner got the best of 49-year-old Rockies starter Jamie Moyer.

Bumgarner (1-1) took a no-hitter into the sixth inning and gave up just one run on four hits and two walks in 7 1/3 to beat Moyer, who was in his fourth MLB season already by the time the Giants starter was even born.

"It was pretty cool to throw against him," said Bumgarner. "I can see why he's still successful."

Melky Cabrera was 2-for-4 with two RBI and Brandon Crawford also had two hits and a run scored for the Giants.

The Pirates arrive in San Francisco still looking for their first road win of the season. Pittsburgh opened its campaign by taking two of three at home over Philadelphia, but was swept in three games at Los Angeles to begin a nine-game trek out west that ends next week in Arizona.

Five of the Pirates' first six games have been decided by just a single run, including yesterday's 3-2 setback. Pittsburgh has allowed just 15 runs through its first six games, but has plated only 11.

The Dodgers got all of their runs in the first inning off Pirates' starter Jeff Karstens, who settled down after the rough beginning to yield seven hits over five frames.

"In the first inning his changeup was good, but he got some elevated and they got good swings on it," said Pittsburgh manager Clint Hurdle. "They put them in places we weren't. After that, he was solid."

Andrew McCutchen went 3-for-3 with a run scored while Michael McKenry hit a solo homer in the loss. McCutchen has reached base safely in all six games so far and has a hit in five straight, batting .474 in that span.

The Pirates go with James McDonald for this opener and the righty made a solid season debut versus the Phillies last Sunday. McDonald gave up two runs on four hits and two walks over six innings, getting a no-decision in his team's eventual 5-4 victory.

A former Dodger, the 27-year-old has faced the Giants 10 times in his career with three starts. He is 1-2 over that time with a 3.08 ERA.

These two clubs split their six meetings a season ago, with the Giants winning two of three at home. San Francisco has won eight of its past 11 at home versus Pittsburgh.