Christian Walker and Jose Altuve socked two-run home runs, and the Houston Astros rallied from an early three-run deficit to defeat the visiting Detroit Tigers 8-5 in the opener of a three-game series Monday.Walker and Altuve struck against Tigers right-hander Jack Flaherty (1-3), with Walker capping a sudden two-out rally in the fourth inning after Flaherty retired the first two batters of that frame.Flaherty faced just one batter over the minimum entering the bottom of the fourth, capitalizing when Altuve was caught stealing in the first inning before inducing Walker to ground into a double play that erased Isaac Paredes in the second. But after Paredes worked a two-out walk in the fourth, Walker blasted his fourth homer 399 feet to left-center field to cut the deficit to 3-2.Flaherty did not record an out in the sixth. Altuve followed a leadoff single from Jeremy Pena with his fourth home run, driving an 0-1 fastball 396 feet to left center. Flaherty departed having allowed four runs on six hits and two walks with four strikeouts.The Tigers spotted Flaherty a 3-0 lead off Astros right-hander Ronel Blanco with their display of prodigious power. Kerry Carpenter clubbed his sixth home run of the season and 50th of his career with two outs in the third, supplying Detroit a 2-0 lead by driving home Trey Sweeney.An inning later, Riley Greene took Blanco deep, blasting his fifth homer to left center. Blanco allowed three runs on three hits and two walks with six strikeouts over five innings.