OAKLAND, Calif. -- Wei-Yin Chen's longest start of his career was his most dominant.
"Not physically, but mentally, I think this is probably the best start I have had in the major leagues," Chen said through an interpreter. "I had a really good feeling today and I felt strong today."
Jim Johnson completed the three-hitter by getting the final three outs for his ninth save. The Orioles have won seven of their past nine games while the A's have dropped seven of eight.
Chen was brilliant, not allowing a runner to reach third base. He struck out five and walked two. The eight innings pitched eclipsed Chen's previous longest outing of 7 2/3 innings May 10 against Texas last season.
"(Chen) had (only) two or three three-ball counts all night. We retired their first batter in all nine innings, and that is big," Orioles manager Buck Showalter said. "(Chen) had good command of his fastball the whole night on both sides of the plate. He was a difference-maker."
The Orioles broke a scoreless tie in the seventh inning as J.J. Hardy led off against Tommy Milone (3-2) with a single that A's right fielder Josh Reddick bobbled for an error, allowing Hardy to go to second. After an out, Steve Pearce drove him in with a sharply hit ball past diving A's shortstop Adam Rosales.
"(Milone) pitched a really good game. He was changing speeds well and hitting his spots," said Pearce, who went 2-for-3 on the night with a double to go along with his RBI single. "He just left a couple of pitches up, and I was able to get extended and get good wood on it."
Baltimore added two runs in the ninth against Oakland reliever Ryan Cook on an error and sacrifice fly. The A's had a season-high three errors.
"When you are in close games like that -- defensive miscues end up really costing you," A's manager Bob Melvin said. "It's maddening for us."
Milone gave up six hits and struck out five while allowing the unearned run.
The Orioles had chances early but Milone worked out of trouble.
"We always feel good when Tommy takes the mound," Melvin said. "Tonight, when you struggle to get hits and don't score runs -- he keeps you in the game."
Chen was hitting his spots with his fastball and his off-speed stuff. He threw 106 pitches in the eight innings, 68 for strikes.
"You could tell he had a good feel for the ball tonight," Showalter said. "He had a good rhythm for everything he was doing."
It was the first three-error game for the A's this season. ... Injured Oakland slugger Yoenis Cespedes (hand) went 2-for-3 with a three-run homer and a walk in his second rehab game Friday night with Triple-A Sacramento. A's manager Bob Melvin said Cespedes was scheduled to play in the field Friday night, DH on Saturday and, if all goes well, be activated Sunday. ... The A's are slated to send A.J. Griffin (2-1, 4.50 ERA) to the mound Saturday to face Orioles starting pitcher Chris Tillman (0-1, 5.23). Griffin has never faced the Orioles. Tillman has one previous career start against the A's (May 27, 2011), allowing one earned run and six hits in 4 1/3 innings. ... The Orioles have not won a season series against the A's since 1998. ... The A's celebrated the 40th anniversary of the club's 1973 World Series title -- the second of three consecutive championships -- on Friday before the game with an autograph session for fans. The celebration will continue before Saturday's game with an on-field reunion honoring the members of the 1973 team.