Jackson will try to earn his fourth victory in as many starts versus Seattle and help the Cubs win their series at Safeco Field on Sunday.Castro was batting .131 (11 for 84) in his first 21 games this month, but is 6 for 19 in his past four and hit his first home run since April 30 in a 5-3 victory in 11 innings Saturday. Soriano had a two-run homer in the 11th and finished 3 for 5 with three RBIs.Soriano is 7 for 18 in his last four games after batting .125 (6 for 48) in his previous 12. He's homered in each of the first two games in the series and is 7 for 12 in his three starts as a designated hitter this season."My swing is there now," Soriano said. "My hand is quick. I feel young. My hand is part of my swing. If my hand is quick, I have a lot of things to do to help the team."The Cubs (34-45) have homered in a season-high nine straight games and Soriano's longball Saturday helped the team recover after Kevin Gregg blew his first save in 13 chances. Chicago's bullpen is 17 for 33 in save opportunities this season and blown an opportunity in each of the first two games of this series.Jackson (3-10, 5.84 ERA) has also yet to shake his inconsistency this season but will face a team he's dominated in the past. The right-hander is 3-0 with a 0.40 ERA, his best against any opponent, against Seattle (35-46).The most recent of those matchups was April 18, 2009, and Jackson enters this game 0-2 with a 9.00 ERA in his last two starts after going 2-0 with a 1.38 ERA in his previous two. He gave up six runs over 4 2/3 innings in Tuesday's 9-3 loss in Milwaukee."We've got to get more consistency," manager Dale Sveum told the team's website. "I think he knows the formula. His good games have been the conviction and the velocity and try to overpower people, and not finesse anything up there."Even if he can find an improved form, Jackson might still have to outduel a resurgent Jeremy Bonderman (1-1, 3.30). The right-hander is 1-0 with a 1.42 ERA in his last four starts but hasn't gotten enough support to earn a victory in any of his last three outings.Despite not having a feel for his curveball, Bonderman gave up two runs in 5 1/3 innings last Sunday against Oakland before the Mariners scored three times in the 10th for a 6-3 victory."I threw one good (curveball) and four or five bad ones, basically lived with the fastball all day. You just have to battle through some starts and try to find a way to keep your team in the game," he told the team's website.Bonderman has never pitched against the Cubs but six of their players have faced him. David DeJesus has the most experience, going 10 for 35 (.286), while Soriano is 3 for 10 with no extra-base hits and Scott Hairston is 3 for 4.Endy Chavez has performed best against Jackson among current Mariners players, going 4 for 7 with a pair of doubles.