C.J. Wilson tossed eight scoreless innings 1 victory over the Athletics in the rubber match of a game series.
Wilson (16-6) scattered five hits and a walk while striking out 11 batters in his third straight win.
Josh Outman (3-5) allowed four runs on eight hits and three walks through 4 2/3 innings as Oakland lost for the fourth time in six games.
Eric Sogard homered to account for the A's lone run.
"Right now we're playing for pride and every loss is a disappointment," said Outman. "You especially want to play better in games against division opponents and that was not the case today."
Craig Gentry led off the fifth inning with a triple just inside the line in left field and was promptly brought home when Ian Kinsler followed with a single to right. Kinsler stole second and moved to third on an Elvis Andrus groundout before crossing the plate on Josh Hamilton's sacrifice fly.
Michael Young reached on an infield single before Beltre hammered a ball into the left-field bleachers to put the Rangers ahead 4-0. The blast was his 300th career home run.
Beltre added a solo shot to center, and Gentry and Andrus had run-scoring singles off of Andrew Carignan in the seventh inning to increase the Rangers' lead.
"He's really getting his timing down and it's the perfect time for him to do it cause we're going to need him for the stretch run," said Texas manager Ron Washington about Beltre.
Matt Treanor's sacrifice fly in the eighth made it an 8-0 game.
Sogard led off ninth with a home run to right field off of Koji Uehara to end the shutout.
Oakland only managed to put runners in scoring position twice against Wilson, leaving a man on third in the second and a man on second in the sixth inning. The A's went 0-for-5 with runners in scoring position and stranded six men on base.
Texas recalled pitcher Michael Kirkman from Triple-A Round Rock Sunday...Oakland selected the contract of outfielder Jai Miller from Triple-A Sacramento Sunday...Beltre became the 132nd player all-time to reach 300 home runs. He also extended his hit streak to 16 games...The game was the Rangers' fifth straight with 12-or-more hits...Outman fell to 1-4 on the road this season...Texas leads the season series, 11-5.