The highly-touted left-hander will try to help the Rangers post a fifth straight victory Saturday night when they continue their four-game home set against the Athletics.Oakland (37-41) fell to 10-15 against left-handed starters after Friday's 4-3 defeat. The Athletics blew a two-run lead after scoring twice in eight innings against the Rangers' Matt Harrison, who earned his 11th victory to tie Tampa Bay's David Price for the AL lead.Washington is choosing to start Perez (0-0, 13.50 ERA) over right-hander Justin Grimm because of Oakland's woes against southpaws. Rated one of Texas' top five prospects by Baseball America each of the last four years, the Venezuela native was recalled Tuesday from Triple-A Round Rock."I feel great. They are giving me this opportunity and I want to do the job," the 21-year-old Perez told the Rangers' official website. "I want to do the same thing I did in spring training: throw the ball over the plate and see what happens."Perez had a rough major league debut in relief Wednesday, allowing four runs and retiring only two batters in a 13-9 victory over Detroit. He went 5-5 with a 4.59 ERA in 15 starts with Round Rock."It will be start to start," Washington said. "He's not going to be etched in stone."Texas (49-29), meanwhile, is 15-9 against left-handed starters. The Rangers will get their second look at Oakland rookie left-hander Tommy Milone (8-5, 3.83), who enters with a 14-inning scoreless streak.Milone gave up four runs over seven innings of a 4-1 loss at Texas on May 16. Josh Hamilton, Craig Gentry and Elvis Andrus each had two hits against him and Adrian Beltre delivered a two-run homer.Milone became the first rookie pitcher in Oakland Athletics history to win eight games before the All-Star break Monday as he scattered seven hits over seven innings in his second straight victory, 1-0 at Seattle."I have expectations for myself, obviously, that is to win games," Milone said. "That's why I'm here."Texas has rallied to post consecutive one-run victories to start this series, coming back from an early three-run deficit in Thursday's 7-6 victory.Friday's win was more dramatic as Gentry's bases-loaded triple in the eighth capped a four-run rally that erased a 2-0 deficit. The hit was aided by Oakland left fielder Yoenis Cespedes, who appeared to misjudge Gentry's deep fly ball.The Rangers managed two hits through seven innings before their winning rally."We weren't hitting the ball that hard early," Washington said. "But we kept grinding and kept grinding. That's why you play nine innings."Texas prevailed without using reliever Mike Adams and closer Joe Nathan, who had both pitched in each of the past three games."Mike Adams and Joe Nathan needed time down," Washington said. "They needed a break."The Athletics, last in the majors with a .225 batting average and last in the AL with a .365 slugging percentage, have dropped 10 of 12 in Arlington.