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. "It was definitely huge to get a win right here today," Texas winning pitcher Matt Harrison said. "It keeps them where they were when they came in here, so it keeps [the lead] at four and it cuts that magic number down a couple of more numbers. If we just keep winning ballgames then we'll be all right." 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 Harrison. The lefty improved to 18-10 but wasn't sharp, laboring through six innings while allowing four runs on seven hits. "Matt wasn't at his best, but he was able to fight through a lot of things and he was able to make pitches when he had to," Rangers manager Ron Washington said. "They had men on base every inning. He was in a little bit of trouble, but he got us through six. That's what we needed." 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 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. "We didn't look good early,' Oakland manager Bob Melvin said. "But to battle back like that, we would have had a chance to tie the game if we got a runner on base in the ninth. That's testament to how good they played." 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. "Although we lost last night, we still were in first place," Washington said "They're still looking up at us. We knew all we had to do was come out and get a good job out of Harry and our pitching staff, put some runs on the board, win a ballgame. Everything else will take care of itself. "Now we don't have to worry about Oakland, we've got Anaheim coming to town. We'll worry about Oakland when we get out there." 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. "We don't have any negative thoughts right now," Reddick said. "It's going to be good to go home. We've been on the road for a month. "We can't rely on L.A. to lose and we can't rely on Texas to fall back. We know we're just not going to back down." NOTES: Washington expects Yu Darvish to take his turn in the rotation Sunday. Darvish missed Tuesday's start with a stiff neck. ... Oakland left-hander 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.