Davis missed a month with a right oblique strain last season, and Mancini capably moved back to first.
"It's always good to have a refresher," Mancini said. "It's not like I think I'm that good to where I don't need some work. I have gotten some work.
"I made sure to start taking some grounders there, but also putting the large majority of my focus on left, too. Because that's not exactly my natural position, so I've been trying to balance it out a little bit, too. I'm ready for anything."
Besides Mancini, the Orioles also have Pedro Alvarez, who started at designated hitter on Thursday, to play first. They brought Garabez Rosa from Minor League camp as insurance for Thursday's game.
Anthony Santander started in place of Mancini on Thursday.
Positional battles Nestor Cortes Jr. fell a step behind in the battle for the fifth starter's job on Thursday, allowing three runs on six hits in three innings.
Cortes is competing with Mike Wright Jr., who pitched three innings of one-run ball on Wednesday; Miguel Castro, who will make his Grapefruit League debut on Friday; and Ynoa.
The advantage for the Rule 5 Draft pick Cortes is that he's left-handed, while Castro, Wright and Ynoa are right-handers. But Cortes now has a 6.43 ERA in three starts. He's allowed 11 hits in seven innings, struck out four and walked none.
"I feel like I was leaving too many pitches over the plate," Cortes said. "I wasn't making them hit my pitch. Just wasn't crisp enough. ... I wasn't making them hit my pitch and I think that's what hurt me today. Too many pitches left over the plate and too many strikes."
Unlike Castro, Wright and Ynoa, Showalter has little experience with Cortes.
"You've got to be careful putting too much [emphasis on] Spring Training, but where he's concerned, that's kind of what you're going by," Showalter said.
Roster moves The Orioles have reassigned right-handed pitcher Perci Garner to Minor League camp. Garner, who pitched three hitless innings this spring, was signed as a Minor League free agent on Dec. 1. He pitched in eight games for the Indians in '16 with a 4.82 ERA.
The Orioles now have 51 players in camp.
Up next Castro makes his Grapefruit League debut when the Orioles travel to Dunedin Stadium to take on the Blue Jays on Friday at 1:07 p.m. ET. The righty has been slowed by tendinitis in his knees and a sore lower back. The game will be broadcast live on Gameday Audio.
Rich Dubroff is a contributor to MLB.com who covered the Orioles on Thursday.