Sean Doolittle and Ryan Madson are on the move as the A's have traded the veteran relievers to the Nationals.
Oakland will receive RHP Blake Treinen, INF Sheldon Neuse and LHP Jesus Luzardo from Washington.
The deal ends Doolittle's six-year run with the A's, which comes on the heels of the end of Stephen Vogt's tenure in Oakland.
Madson is in the second year of a three-year, $22 million deal.
In 23 games this season, Doolittle has a 3.38 ERA and three saves, while Madson posted a 2.08 ERA in 40 appearances.
Treinen returns to the team that drafted him in the seventh round of the 2011 MLB Draft. The A's traded Treinen in 2013 as part of a three-team deal involving the Nationals and Mariners. The 29-year-old has struggled this season to the tune of a 5.73 ERA in 37 games.
Neuse, the Nationals' No. 6 prospect according to MLBPipeline.com, is hitting .291 with nine homers and 51 RBI for Low-A Hagerstown.
Luzardo is a 19-year-old left-handed pitcher just getting his start in pro ball. Drafted in the third round of the 2016 MLB Draft, Luzardo has pitched in just three games for the Rookie-ball Gulf Coast League Nationals. Despite his lack of experience, MLBPipeline.com had Luzardo ranked as Washington's No. 10 prospect.
For the second straight season, Kendall Graveman will get the ball on Opening Day for the A's. And for the second straight year, he'll face Mike Trout and the Angels.
The team made the news official on Tuesday morning.
Last year, in a win over the Angels, Graveman went six innings, allowed two earned runs and struck out seven.
"It's something I don't take for granted. It's an honor and a privilege and [I just want to] try to get the season off to a good start and hopefully be a leader of this staff," Graveman told reporters Tuesday in Arizona.
In four seasons with the A's and Blue Jays, Graveman has a 4.11 ERA in 76 appearances.
UPDATE (Mar. 19, 7:45 p.m. PT): The A's officially announced the Cahill signing on Monday. This story has been updated to reflect that.
On the same day the Oakland A's learned they'd be without Jharel Cotton all season, they signed a familiar face to bolster their pitching depth.
Oakland agreed to a one-year deal with Trevor Cahill, nearly 12 years after the A's drafted him in the second round.
Cahill pitched for Oakland from 2009-11. He started 96 games in three seasons with the A's, going 40-35 with a 3.91 ERA and 1.32 WHIP. Since Oakland traded him to the Arizona Diamondbacks in Dec. 2011, Cahill's pitched for six teams.
The 30-year-old won a World Series ring with the Chicago Cubs in 2016, and pitched for the San Diego Padres and Kansas City Royals last season. In 2017, he went 4-3 in 21 appearances (14 starts) with a 4.93 ERA and 1.62 WHIP.