Sizemore's grand slam in the sixth inning helped the A's end a nine-game skid against Texas with an 8-7 victory over the AL West-leading Rangers on Saturday.
Manager Bob Melvin was tired of losing to the A's division rival, and he let the players know how he felt following Friday night's 13-4 defeat to Texas.
"These guys kind of had our number," Sizemore said. "Skip (Melvin) let us know (Friday) night that we had to put that behind us and come out (Saturday)."
With the score tied at 3, Rangers starter Alexi Ogando (12-8) hit Josh Willingham with a pitch leading off the sixth, and David DeJesus followed with a single. Texas manager Ron Washington replaced Ogando with left-hander Mike Gonzalez.
Ryan Sweeney attempted to bunt, and Gonzalez made a nice play to get a force at third. After Brandon Allen was retired on a foul popup, Gonzalez walked Kurt Suzuki to load the bases, and Washington again went to his bullpen and brought in Yoshinori Tateyama.
Sizemore was sent in by manager Bob Melvin to hit for Eric Sogard, and Sizemore ripped Tateyama's high 1-0 fastball into the left field seats for his first career grand slam and a 7-3 lead.
Cliff Pennington added an RBI double off Tateyama later in the sixth to give the A's a five-run cushion.
Sizemore had his second career pinch homer, but a defensive play he made in the ninth at third base nearly matched his deep drive with the bases loaded. Sizemore leaned into the Oakland dugout to catch Ian Kinsler's foul popup leading off the ninth, with catcher Suzuki grabbing Sizemore by the belt to make sure his teammate didn't tumble into the dugout.
Asked to compare the two plays, Sizemore smiled and said, "I've got to say the grand slam. You don't hit too many pinch-hit grand slams."
Tateyama also allowed a grand slam to Boston's Carl Crawford last Saturday at Boston, the final batter he faced in that game. For the first time in Rangers history, a pitcher gave up grand slams to consecutive hitters.
According to research provided to the Rangers by Elias Sports Bureau, the last pitcher to allow grand slams to consecutive batters faced was Greg McCarthy of Seattle in 1998.
In his last five outings, Tateyama has been knocked around for 12 runs and 11 hits and four homers in four innings.
"The location is not there," the Japanese right-hander said through a translator.
Adrian Beltre's 299th career homer -- a two-run shot in the sixth off starter Trevor Cahill (11-13) -- pulled Texas within 8-5. Michael Young's two-run single in the seventh off Fautino De Los Santos made it 8-7.
Beltre, who had three hits to extend his hitting streak to 15 games, was the final batter for Cahill, who gave up five runs and seven hits over five-plus innings.
Andrew Bailey pitched the ninth for his 20th save in 22 chances, but it wasn't easy. Josh Hamilton drew a two-out walk, and Michael Young reached on an infield single, but Beltre lined out to second baseman Adam Rosales to end the game.
Hamilton hit a two-run game-winning homer off Bailey on July 9 and was 3 for 3 for his career against the A's closer. So Bailey wasn't going to give the slugger anything he could knock out of the ballpark.
"Obviously, everyone knows he hit the walk-off against me," Bailey said. "I wasn't trying to stay away from him or walk him, but I knew I had to be careful."
Ogando gave up five runs -- three earned -- and six hits in five-plus innings in his first for the Rangers since Aug. 31. His previously scheduled start was skipped to allow him additional rest.
Ogando had gone 7-0 in his first 12 starts but the converted reliever has struggled with his command and has dropped five of his last seven decisions.
"He kept us in the ball game," Washington said. "He's coming back. I felt like he did what he had to do."
Willingham led off the second with a line drive single up the middle that Ogando had to duck to avoid. DeJesus bunted, and catcher Yorvit Torrealba threw wildly to first for an error that allowed the runners to advance to second and third.
Sweeney followed with a two-run triple into the right field corner, and Suzuki added a sacrifice fly later in the inning for a 3-0 pad.
The Rangers got a run in the third when Ian Kinsler scored from third on Cahill's wild pitch, and Mitch Moreland's two-run double in the fourth pulled Texas even at 3.
Rangers OF Nelson Cruz ran the bases for a second straight day as he rehabs from a strained left hamstring that put him on the 15-day DL on Aug. 30. The plan is for Cruz to take Sunday off from running on the field, then reevaluate his condition early next week. ... Hamilton was back in the lineup after missing Friday night's game to be with his wife for the birth of their fourth daughter. ... Oakland LHP Josh Outman gets a spot start on Sunday, replacing RHP Rich Harden. Outman will be making his ninth start of the season but his first since July 2. Outman struck out seven Boston hitters in a four-inning relief stint Aug. 27, but has pitched only 2 1/3 innings in two appearances since then. ... Harden won't start again until Wednesday night for extra rest. Rangers ace C.J. Wilson, a 15-game winner, takes the mound for Texas. ... OF Coco Crisp missed Saturday's game and has been ruled out for Sunday due to injuries to his ankle and foot.