The Rangers' fourth straight victory and eighth in their last nine games reduced their magic number to three for clinching the division. The Rangers remained five games ahead of the Angels, who won at Toronto Wednesday night.
Texas concludes this three-game series Thursday afternoon and then can cement its second playoff berth in 12 years in Arlington over the weekend against last-place Seattle. They conclude the season with a three-game set in Anaheim.
On a day the Athletics stripped the interim tag from manager Bob Melvin and rewarded him with a three-year contract through the 2014 season, the host team failed to hold onto a late lead and lost for the third straight time.
Kinsler led off the eighth with his 30th homer of the year, a shot to left field on a full-count offering. One out later, Hamilton went deep to right field off Balfour (4-2).
Mike Adams threw a perfect eighth inning after Koji Uehara (2-3) held the A's down in the seventh. Neftali Feliz walked Josh Willingham leading off the bottom of the ninth, but retired the next three hitters to lock down his 29th save.
"It was fun, a little stressful, but fun," Hamilton said.
The A's went ahead in the fifth against Texas starter C.J. Wilson. Cliff Pennington doubled with one out and Brandon Allen's line drive single to left field tied the contest. Michael Taylor's walk led to a Jemile Weeks ground single into left field, moving Oakland in front.
"He's just a tough kid who feels really good in those situations when he goes up there," Melvin said of Weeks.
Napoli went 2-for-4 for the Rangers and is now batting .552 (16-for-29) over his current eight-game hitting streak...The Rangers have won 15 of the last 22 on the road...Texas is 13-5 vs. Oakland this season, winning the last three and 12 of the last 13 beginning May 10...The A's are 18-25 in one-run games...Wilson gave up five hits and fanned eight before leaving after the sixth inning...McCarthy threw seven frames.