OAKLAND, Calif. -- Right-hander Kendall Graveman got back on track and the Oakland Athletics' three Matts -- Chapman, Joyce and Olson -- each went deep Sunday afternoon in a 9-3 victory over the Baltimore Orioles at Oakland Coliseum.

The A's picked up a split in the four-game series and delivered a blow to the Orioles' wild-card playoff push.

Graveman (3-3) posted his first win in three starts since being reinstated from the disabled list on Aug. 1 after missing more than two months with a strained right shoulder. He allowed two runs and eight hits with a season-high eight strikeouts and one walk in seven innings.

Graveman gave up both runs and five hits in the first two innings. Then he gave up back-to-back singles to open the third before settling down.

"I think I found the groove I thought I was in before I got injured," Graveman said. "The arm felt great all night. I think I'm finally getting back on track."

Chapman hit a three-run shot, his eighth homer of the season, during a five-run fourth inning. Joyce hit a two-run blast, his 16th homer of the season, in the seventh.

Olson added a solo shot in the eighth, homering for the third straight game, this time against left-hander Zach Britton, who hadn't allowed a homer to a left-handed hitter since April 29, 2013. The homer was his Olson's seventh of the season.

"There's a lot of times where I pick and choose, maybe looking inside if a team's pitching me a certain way, and that being the case against Britton," Olson said. "They'd been throwing me inside a pretty decent amount, especially the lefties. I took a pitch and sat on an inside pitch. I got it."

Manny Machado went 3-for-4 with a triple and his 22nd home run for the Orioles, a solo shot leading off the eighth.

Right-hander Jeremy Hellickson (7-7) made his third start since coming to the Orioles from Philadelphia in a trade on July 28 and failed to have a quality start for the first time.

Hellickson, who is 1-2 as an Oriole, gave up six runs and five hits, including Chapman's home run, in five innings with five strikeouts and two walks.

"When you give up three or four hard-hit balls and you give up six runs, it's just frustrating," Hellickson said.

The Orioles took a 1-0 lead in the first inning when Machado tripled down the right field line and Jonathan Schoop lined an RBI single. They extended their lead to 2-0 in the second. Mark Trumbo led off with a double and Chris Davis singled him home. After that, Graveman threw five straight shutout innings.

"We knew Graveman, once he got his feet on the ground, he's solid," Orioles manager Buck Showalter said. "Both pitchers were using the benefit of a couple inches off the plate. There were a lot of strikes called today that weren't strikes, but both pitchers benefited from it. I think he did a little better job of it."

Oakland scored five runs in the fourth to build a 5-2 lead. Marcus Semien lined a leadoff single, moved to second with one out on a walk to Khris Davis and scored on Ryon Healy's opposite-field double grounded down the right field line.

The A's pulled even when Olson hit a ground ball, and Khris Davis beat first baseman Chris Davis' throw home.

That brought Chapman to the plate, and he lined Hellickson's 1-2 changeup over the left field fence for a three-run shot, giving Oakland a 5-2 lead.

"He did a good job of getting it," Hellickson said. "It wasn't a terrible pitch, but I think I threw four in a row pretty much in the exact same spot. It was a good pitch. He went down and got it."

The A's made it 6-2 in the fifth. Joyce lined a leadoff double off the left field fence, stole third base and scored on Semien's sacrifice fly to left field. Oakland extended its lead to 8-2 in the seventh on Joyce's two-run blast off left-handed reliever Richard Bleier.

"He's had a really good year for us after a real slow start," A's manager Bob Melvin said of Joyce. "To put up 16 homers. He's had real solid contact off lefties where I don't just have to pinch hit for him. A home run like that, and defensively he does a nice job for us."

At that point, Orioles right-hander Chris Tillman took over for his first career relief appearance after 194 starts. He pitched 1 1/3 perfect innings with two strikeouts. Tillman went 1-7 with a 8.10 ERA in 15 starts this season.

"As proud a man as he is, it feels good for us to know that he feels like that arrow's pointed up," Showalter said. "Creates some interesting options as we go forward."

Shortstop Tim Beckham went 0-for-4, ending his 12-game hitting streak to start his Orioles career.

NOTES: Orioles OF Anthony Santander (right forearm strain) is expected to be officially activated from the disabled list on Thursday, two days after his rehab assignment with Double-A Bowie ends, Baltimore manager Buck Showalter said. He said the Orioles have 48 hours to activate Santander after his rehab assignment ends. Santander is a Rule 5 Draft selection from Cleveland and must remain with the Orioles for the entire season or be offered back to the Indians for $25,000. ... Oakland C Josh Phegley (strained left oblique) will work out with the A's again Monday, and if all goes well he'll likely begin a rehab assignment with Triple-A Nashville on Tuesday or Wednesday, manager Bob Melvin said. ... LHP Sean Manaea, who gave up six runs and six hits in one-third of an inning Saturday in a 12-5 loss to Baltimore, is expected to make his next scheduled start, Melvin said. "He basically got almost a (skipped turn) last night in that he threw (28) pitches," Melvin said. "I don't know that after an outing like that you'd skip a start. I mean anything's possible, but I don't' think that's one of the options right now."