Looking to sweep their opening series for the first time in 12 years, the Diamondbacks try for an eighth consecutive victory over the visiting Giants on Sunday at Chase Field.A big reason for Arizona's surprise run to the NL West title last year was the 48 times the club rallied to win games. Through the first two games of 2012, the Diamondbacks (2-0) have scored half of their 10 runs in the first inning.After Chris Young and Paul Goldschmidt each hit first-inning homers in Friday's 5-4 win over San Francisco, Aaron Hill homered in the first and Young had the first of his two run-scoring doubles in the same inning as the Diamondbacks won by the same score Saturday."It's a good way to start, put runs on the board," manager Kirk Gibson said.The Diamondbacks' seven-game winning streak over the Giants (0-2) is their longest in the series. Arizona's last opening series sweep came against Philadelphia in 2000.Young is 3 for 7 with four RBIs in the first two games, while Hill homered twice and drove in three runs after going 0 for 4 in the opener.After roughing up Tim Lincecum and Madison Bumgarner in the first two games of the series, the Diamondbacks hope to get the best of Matt Cain, who is 6-2 with a 2.92 ERA in his last nine starts against them.The right-hander had won three straight starts at Chase Field before he allowed three runs in 7 1/3 innings of a 3-1 loss there Sept. 23.Cain takes the mound less than a week after he signed a $127.5 million, six-year contract, the largest deal for a right-handed pitcher in baseball history."This kid literally has gotten better each year and has proved that under very difficult circumstances," general manager Brian Sabean said.Cain was 12-11 in 33 starts last season but finished with a 2.88 ERA while receiving an average 3.61 runs of support, among the lowest in the majors.Pablo Sandoval and pinch-hitter Brett Pill each hit two-run homers Saturday for San Francisco, which has totaled 15 runs during a six-game skid at Chase Field.The Giants have not been swept in a season-opening series of at least three games since 1969."The guys are trying to get settled in," manager Bruce Bochy said. "We battled back (first two games) and that is a good sign."Sandoval is 4 for 8 with three RBIs through two games, but 1 for 6 versus scheduled Arizona starter Josh Collmenter.After being called up from the minors in mid-April, the right-hander made his first seven appearances out of the bullpen before going 9-10 with a 3.59 ERA in 24 starts in 2011. His 10 victories overall matched a club record for rookies.Though Collmenter went 0-4 with a 9.95 ERA in six starts and battled some forearm stiffness during spring training, Gibson expects good things from his young starter in 2012."We're confident in what he's going to do," Gibson told the Diamondbacks' official website.Collmenter, who earned the win in his major league debut April 17 against the Giants, was 1-1 with a 5.25 ERA as a starter versus San Francisco last year.