Lou Trivino (2-0) induced Peterson's inning-ending double play in the sixth for the win. Blake Treinen finished for his fourth save in six chances after Semien's RBI single in the eighth provided insurance.
Lucroy played his 1,000th career game and had three hits for the A's, who had lost four of five. Oakland didn't take batting practice after a late arrival home from Seattle and three straight days of pregame hitting at Safeco Field.
Mengden - just 1-10 in 16 career starts pitching at home in the Coliseum - struck out five over five innings, allowing three hits and one run before Yusmeiro Petit gave it up in his third appearance since his mother's death.
Center fielder Jones played in his 1,500th game for the Orioles, becoming the eighth to do so - joining company that includes Cal Ripken Jr.
Orioles manager Buck Showalter in ponder mode on A's great Vida Blue: "Was Vida Blue his real name? Great name. You don't hear names like that anymore. If I was Vida Showalter, who knows what would have happened. I would have been a star."
Orioles: 2B Jonathan Schoop, on the disabled list since April 14 with a strained right oblique muscle, will continue his rehab assignment this weekend perhaps going from Double-A Bowie to Triple-A Norfolk given potential weather issues and a better chance to play in top conditions. "I want him to be healthy," Showalter said. "The worst thing would be to rush this and he comes back and his first at-bat he goes back to square one. We're ahead of schedule for what normally happens with an oblique muscle." ... LHP closer Zach Britton, recovering from surgery on his right Achilles tendon, threw Friday and was scheduled to do pitcher fielding practice Saturday.
Athletics: RHP Paul Blackburn, on the DL since March 26 with a strained pitching forearm, threw off flat ground and is expected to pitch off a mound sometime this homestand. Manager Bob Melvin said it's too soon to know whether Blackburn will be ready to be activated when eligible May 25. ... LHP Ryan Buchter, dealing with a strained throwing shoulder, is not yet back to playing catch. He's still in the strengthening phase. ... RHP Liam Hendriks (strained right groin) is playing catch but is yet to throw off the mound.
Orioles: RHP Kevin Gausman (2-2, 4.15 ERA) tries to win consecutive starts for the first time in 2018.
Athletics: RHP Trevor Cahill (1-1, 3.00) makes his fourth start since being called up April 17, having gone 0-1 with a 4.91 ERA over his past two starts - both on the road.