By Art Garcia ARLINGTON, Texas - The Texas Rangers took another big step toward their third straight American League West crown with Thursday afternoon's 9-7 victory over the hard-charging Oakland A's. Texas (92-64) split the four-game series at Rangers Ballpark to reduce its magic number to clinch the AL West to three games with six games left in the regular season. While winning the division is a long shot for Oakland, the A's are still in position to claim one of the two Wild Card spots. Oakland hasn't been in the playoffs since 2006, while the Rangers have reached the World Series the last two years. Texas got the series split by jumping on their closest divisional pursuers with an early power display. Ian Kinsler led off the first with a home run, and Mike Napoli added a two-run shot later in the inning, as the Rangers took a 5-0 lead. Kinsler's seven leadoff home runs this season lead the Majors, while also tying his career high for a season. After Texas had scored a total of five runs while losing the two previous nights, the power surge was a welcome sight for Texas starter Matt Harrison. The lefty improved to 18-10 but wasn't sharp, laboring through six innings while allowing four runs on seven hits. Harrison, Texas' first 18-game winner since Kenny Rogers in 2004, gave up home runs to Josh Reddick and Derek Norris before departing. Oakland starter Travis Blackley (5-4) lasted only the first inning. Texas took a 9-4 lead into the eighth before the A's made things interesting by pounding three homers against Rangers reliever Mike Adams in the eighth. Reddick had his second of the day in the surge, preceding shots by Yoenis Cespedes and Brandon Moss. Texas reliever Koji Uehara got the last out in the eighth before Joe Nathan pitched a perfect ninth, including two strikeouts, to nail down his 36th save. The Rangers take their four-game lead over the A's into a three-game home series with the Los Angeles Angels starting Friday. Texas finishes up the regular season with three games at Oakland beginning Monday. The Rangers hope the West is sewn up by then, while the A's could conceivably be playing for either the division or a Wild Card. NOTES: Texas manager Ron Washington expects Yu Darvish to take his turn in the rotation Sunday. Darvish missed Tuesday's start with a stiff neck. ... Oakland lefthander Brett Anderson (right oblique strain) hopes to return for the playoffs if Oakland makes it to the postseason. ... Rangers outfielder David Murphy didn't start for the first time in September.