OAKLAND, Calif. -- Roy Oswalt threw one curveball clocked at 57 mph. His fastball hit 91.

In vintage Oswalt style, the right-hander used his wide-ranging repertoire to baffle Oakland's batters and beat the Athletics for the first time, leading the Texas Rangers to a 6-1 victory Tuesday night.

Oswalt worked ahead and painted the corners the like pitcher of old at age 34.

"That's me, that's my game," Oswalt said. "I'm the same pitcher I've been the last 12 years."

Josh Hamilton and Adrian Beltre each hit solo home runs for Texas.

Elvis Andrus, Craig Gentry and Mike Napoli hit RBI singles off Bartolo Colon (6-8) for the AL West-leading Rangers, who snapped the A's four-game winning streak and avenged a June loss to Colon in the Coliseum.

Oswalt (3-1) struck out six and didn't walk anyone in 6 1/3 innings, retiring 15 of the final 17 hitters he faced in his fifth start of the year and first against the A's. The crafty right-hander had never beaten Oakland in two previous outings, including a loss at the Coliseum on June 7, 2002.

This time, he did it by mixing speeds and pitches to keep Oakland's hitters off balance. He struck out Seth Smith to end the sixth on a 71 mph off-speed offering.

While Oswalt would have liked to finish the seventh, he knows he is making progress with every appearance since signing a minor league deal May 29 before his call up on June 22.

"I'm getting close. I feel better," he said. "The hitters have 300 at-bats behind them and have seen a lot of pitchers, and I'm trying to get up to speed."

The Rangers won for the fifth time in six games but just the third time in their past seven road contests.

Hamilton struck out three times before connecting for his 28th home run to lead off the eighth. He added a sacrifice fly in the ninth. The All-Star slugger kept his average right at .300, and hasn't dipped below that mark all season -- though he did briefly during the game.

"I hadn't really paid attention to it. I knew I was going down the last month to month and a half," Hamilton said. "I'm not really panicking at all."

Josh Reddick homered for the A's, who had some momentum after a three-game sweep at Minnesota only to come home and face the two-time reigning AL champions. Oakland missed an opportunity with the bases loaded in the eighth.

Reddick didn't consider Oswalt's night all that special even though the A's managed just three hits against the veteran pitcher.

"I don't feel like he was very good. I felt like we had a lot of swing-and-misses," Reddick said. "We had a pretty good go at him. We saw a lot of pitches early. Just bad swings in front of the ball. I don't feel like his stuff was very far out there."

Colon, who tossed eight scoreless innings to beat the Rangers on June 6 in the Coliseum, was tagged for eight hits and four runs in seven innings. He remained winless in three starts since coming off the disabled list from a strained oblique muscle. He fell to 2-6 at home this season and hasn't won in four outings since June 12 at Colorado.

The right-hander is 18-7 against Texas in 29 career starts for his most wins against any opponent -- and 19 would have matched Hall of Famer Bert Blyleven, Dennis Leonard and Jack Morris for most by any pitcher.

In Texas' three-run fourth started by Beltre's 17th home run, the Rangers scored on a squeeze when Colon fielded the ball and opted not to throw to first when second baseman Jemile Weeks worked to cover the bag. Colon took the blame.

Oakland, 9-2 in July, failed to move four games over .500 for the first time since May 31, 2010. The A's have never won their first four games after the All-Star break.

Oakland slugger Yoenis Cespedes, nursing a sprained left thumb, doubled among his two hits as designated hitter and hopes to be back in the outfield Wednesday afternoon if he is able to put his hand in the glove without discomfort. He struck out for the second out of the eighth.

Oswalt struck out the side in the fourth, when he gave up only a single to Cespedes.

The bottom of Oakland's order isn't producing.

"You have to stick with guys," manager Bob Melvin said. "We've been pretty good offensively even though some guys have been struggling. When guys aren't hitting you expect the rest of the lineup to be able to pick you up."

Game notes

Rangers 1B Mitch Moreland, on the 15-day DL since June 22 with a strained left hamstring, did baseball activity and is scheduled to do extensive work fielding groundballs Friday with the hopes he will begin a rehab assignment Monday. ... A's OF Coco Crisp was out of the lineup for a third straight game with a sore left shoulder he aggravated on Friday night at Minnesota. Crisp hit and did baseball work and could be in the lineup Wednesday. He saw a doctor and has no structural damage. ... LHP Brett Anderson, recovering from Tommy John elbow reconstructive surgery, faced hitters Monday in a three-inning simulated game and will throw a bullpen session Wednesday. If all goes well, he will begin a rehab assignment with Class A Stockton this weekend. ... Oakland opening day RHP starter Brandon McCarthy (strained throwing shoulder) will throw a bullpen Wednesday. ... The Rangers are scheduled to activate RHP Colby Lewis (6-6) from the DL to start Wednesday afternoon against LHP Travis Blackley (2-2). ... A's OF Jonny Gomes received the "Heart & Hustle Award" in a pregame ceremony. ... A's reliever Jim Miller rejoined the team after he and wife, Tasha, welcomed son Ethan James on Thursday in Virginia.