BALTIMORE -- A steady rain postponed the first game of a three-game series between the Baltimore Orioles and Oakland Athletics on Friday.

The game will be made up as a split doubleheader on Saturday, with the first game scheduled for 1:05 p.m. and the night cap at 7:05 p.m.

The A's will start Rich Hill (3-3, 2.53 ERA), who was scheduled to pitch on Friday, in the first game. Jesse Hahn (1-0, 0.00) will stay on schedule and start the nightcap.

Baltimore's Mike Wright (1-2, 5.40), who was the scheduled starter Saturday, will move up and pitch the day game. Friday's scheduled starter Ubaldo Jimenez (1-3, 5.20) will now take the mound in the second game.

"They said it was going to rain all night and we'll play two games tomorrow," said Oakland manager Bob Melvin, who was informed of the decision at 6:25 p.m., about 40 minutes prior to the scheduled first pitch. "Looking at the weather today, you thought maybe this was going to happen."

Both teams are allowed to add a 26th player to the roster for the second game Saturday. Melvin did not know who would be called up. Orioles manager Buck Showalter did not speak with reporters after it was announced the game was postponed. Both teams, however, would likely add a pitcher for the bullpen.

Because of the double-header, Melvin will also need a new starter for Wednesday's game in Boston.

"We're going to have to look at that and we'll see how we get through (Saturday)," Melvin said. "I really have no idea at this point."

NOTES: Oakland 3B Danny Valencia was activated Friday following his 15-day stint on the disabled list with a minor hamstring strain. "Since he's been here, he's been a force for us," manager Bob Melvin said. In a corresponding move, the A's optioned INF/OF Tyler Ladendorf to Triple-A Nashville. ... RHP Zach Britton felt good after making his first appearance in almost a week Thursday against the Yankees. Britton injured his left ankle Saturday against the White Sox. ... Oakland RHP Chris Bassitt underwent Tommy John surgery Friday with recovery expected to take between 12-18 months. "Surgery was a success," he wrote on Twitter.