OAKLAND, Calif. -- Dan Haren called the first inning an adjustment period. He was working with a new catcher for the first time and they were feeling each other out.
Haren was throwing to new starter Kurt Suzuki for the first time, after Jason Kendall was traded to the Chicago Cubs earlier this week.
"I know I'm not an easy pitcher to catch," Haren said. "As the game went along we got more into a rhythm. That's the first of many. He's going to be around for a while."
After allowing a pair of first-inning runs, Haren (11-3) found his rhythm and retired 17 of the next 20 batters he faced. He gave up three runs and seven hits over 6 2/3 innings to maintain his AL-leading ERA at 2.40. Haren walked two and struck out seven.
"I went out for the second thinking to myself that it's a fresh game, it's 0-0," Haren said. "I went through a dead period the last couple of starts but I feel more life in my arm finally."
Despite the victory, the A's have won just twice in their last 12 games to slip 10½ games behind the AL West leading Los Angeles Angels. Normally a second half team, Oakland is 8-20 since June 18 while the Orioles are 14-13 over the same span.
Haren, who beat the Orioles for the third time this year, gave the A's a much needed lift. Santiago Casilla got four outs and Alan Embree pitched the ninth for his 10th save in 12 chances.
"There were a lot of outstanding things with our team," A's manager Bob Geren said. "Haren battled through it. He didn't have a bad first inning but he settled in and looked like a true ace. He just kept at it."
Steve Trachsel (5-7) lasted 5 1/3 innings in his return from the disabled list. The right-hander, recovered from a strained gluteus muscle, gave up four runs and matched his season-high with nine hits. He walked three and struck out three in losing his third straight decision.
"I felt strong and overall I thought I pitched pretty good," Trachsel said. "I made one mistake to (Jack) Cust and that was the difference."
Trachsel, who fell to 2-7 on the road, has given up 23 runs and 37 hits over his last 23 2/3 innings (8.75 ERA) since beating the Colorado Rockies on June 8.
"It's the same thing," Orioles manager Dave Trembley said. "We couldn't get the hit with two outs."
Kevin Millar's two-run double gave the Orioles the early advantage. In the bottom of the first, Mike Piazza singled home a run and Mark Ellis scored on Eric Chavez's double play grounder to tie it.
Suzuki's fourth-inning sacrifice fly gave the A's a 3-2 edge. Cust hit his 17th home run, and just his second since July 3, to put the A's up 4-2.
Cust and Piazza were in the lineup together for the first time.
"It's amazing how he has come on as a big league hitter," Piazza said. "He has a great command of the strike zone. Maybe we can get some synergy going and help each other to get better."
Corey Patterson, who had two hits, singled with two outs in the seventh to make it 4-3.
Patterson extended his hitting streak to nine games. He also stole second and third in the first, his second multi-stolen base game, and his first since May 27 when he swiped three against the A's in Baltimore.
The Orioles were 2-for-12 with runners in scoring position. Brian Roberts thought that had more to do with Haren than anything.
"When he gets guys on he goes to his split a lot more and that's as good as it gets," Roberts said. "He pitches well and gets guys out and that's how he has the ERA he has. That's a good pitcher doing what he's done all year."
A's closer Huston Street pitched a scoreless inning in his first rehab appearance with Triple-A Sacramento. ... Cust was 0-for-11 against Baltimore pitching before his home run. ... Suzuki broke an 0-for-21 streak with his first-inning single. ... Orioles SS Miguel Tejada returned to Baltimore for a doctor's appointment on Tuesday to determine if the fracture in his left wrist has healed enough for him to begin taking batting practice. ... Haren is 11-0 when given at least two runs of support. ... Mike Piazza Bobblehead Day drew a crowd of 30,828.