Bobby Crosby had three hits and drove in a run as the A's snapped a four-game losing streak and got starter Trevor Cahill his first major league win.
Jack Hannahan doubled home a run and Kurt Suzuki added three hits in the A's highest scoring game this season.
Cahill (1-2) allowed five hits over seven innings without walking a batter, and struck out four.
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Brandon McCarthy (3-1) allowed seven runs on seven hits and three walks.
Chris Davis homered for the Rangers, who had their five-game winning streak stopped. Marlon Byrd and Michael Young each doubled twice, and Young extended his hitting streak to 11 games.
Kris Benson pitched three innings in his first career relief appearance after 197 starts. Holliday greeted him with his fourth home run to give the A's an 8-1 lead. Benson gave up two runs on five hits.
After Cahill gave up Davis' solo shot in the fifth, he retired eight of his last nine batters. He never faced more than four batters in an inning and was the first Oakland starter to pitch into the seventh inning in 14 games.
McCarthy breezed through the first three innings and then ran into trouble in the fourth. Suzuki singled and Jason Giambi and Holliday each walked ahead of Cust's drive halfway up the right field bleachers for his second career grand slam. Hannahan added a run-scoring double.
McCarthy's day was finished after Suzuki and Giambi singled to start the fifth. After Holliday made it a seven-run game, Crosby doubled home a run.
The Rangers scored three runs in the ninth, all charged to A's closer Brad Ziegler, taking advantage of Orlando Cabrera's fielding error and getting RBI doubles from David Murphy and Omar Vizquel and a run-scoring single from Jarrod Saltalamacchia, who had two hits.
Notes:@ Holliday has four home runs in his last 12 games after going homerless in his first 13. ... Cahill received run support of three or less in his first five starts. ... Cust hit his other grand slam at Detroit on Aug. 10, 2007. ... McCarthy had a career ERA of 11.57 (five games) in Oakland. ... The Rangers have homered in all 14 of their road games. ... Young has hit safely in 18 of his last 19 games against the A's.