OAKLAND, Calif. -- Frank Thomas has thrived during pennant races.
"I was looking to hit a home run in that situation because we needed it right there," said Thomas, who has 477 career home runs. "I've learned over the years of how to hit homers the proper way and not just go for the fence. You slow everything down and put an aggressive swing on it."
The A's moved 8½ games up on the Los Angeles Angels in the AL West, their largest lead since September of 1992.
Thomas, who watched from the sidelines during the Chicago White Sox's run to the world championship last year, recorded his third straight multi-hit game and upped his average to a season-high .272. He's batting .339 (41-for-121) over his last 35 games.
"I've been in these situations before a few times and this is when you have to maximize it," Thomas said. "When you get here, you have to step on the gas."
Mark Ellis also drove in two runs for the A's, who won their fourth straight overall and improved to 27-7 since July 25.
The A's played their major-league high 43rd one-run game, winning 18 of the past 22 close contests and improving to 25-18 overall.
"This team has shown a lot of character this year," Thomas said. "We seem to find a way to get it done even when someone goes down. The pitching has been great all year and the offense always seems to get the big hit somehow."
Mora had three hits, including a home run, and drove in two runs for the Orioles, who lost for the third time in four games. Jeff Fiorentino also drove in two runs.
"It was easy for me but I just threw badly," Mora said of his error. "You have to make that play because you can't let the big guy come to the plate."
Orioles starter Erik Bedard hasn't won in his last seven starts. He gave up three runs and six hits, striking out six and walking four.
Todd Williams (2-4) got Jason Kendall and Bobby Kielty on groundouts to open the seventh. Mora fielded Bradley's grounder down the line, planted and threw wide at first. Thomas followed with his home run.
"I just tried to sink one and I made a mistake," Williams said. "It wasn't a very good pitch and he still hit it out. My inning turned into a fiasco for me."
Oakland starter Joe Blanton allowed four runs and seven hits in six innings.
"I really didn't have anything to work with so I had to throw everything at them and try not to walk guys," Blanton said. "We won, so I'm happy."
Mora gave the Orioles a quick lead in the first when he hit Blanton's 2-1 pitch into the left field bleachers. It was Mora's first extra base hit and home run since Aug. 18. It also snapped Blanton's career-best 46-inning, 203-batter homerless streak.
Ellis' two-out double in the second scored Jay Payton to tie the game, and his fourth-inning single put the A's ahead 2-1.
David Newhan and Mora hit back-to-back two-out doubles in the fifth to tie the game and Fiorentino -- playing in the majors for the first time in more than a year -- singled home two runs in the sixth to put the Orioles up 4-2.
- A's 3B Eric Chavez missed the game when an MRI on Thursday revealed a moderate sprain on the inside of his right ankle.
- Orioles C Ramon Hernandez missed his second game with a strained ribcage.
- Orioles OF Corey Patterson missed his third straight with a sprained AC joint in his shoulder.
- A's RHPs Huston Street and Rich Harden each threw a bullpen session of 30 pitches.
- Fiorentino appeared in 13 games last year for the Orioles.
- The A's allowed more than three runs for the first time in eight games.
- The A's won 10 straight at home for the first time since winning 12 straight between Aug. 13-Sept. 2, 2002.