The Orioles already faced looming roster decisions before they officially placed first baseman Chris Davis on the 15-day disabled list before Sunday's game against the Kansas City Royals. And now the club's roster management is about to get trickier.

With Davis on the disabled list and no corresponding move announced Sunday, the Orioles are down one player on their 25-man roster. That's not a concern with Monday's day off. And Orioles manager Buck Showalter said the club expects to have 25 active players for the opening of a two-game series against the Pittsburgh Pirates.

"We'll be at 25 on Tuesday," Showalter said.

Things will get a little more complicated Wednesday, however, when left-hander Troy Patton comes off the suspended list. He has missed the first 25 games of the season for testing positive for amphetamine use (Adderall) last September.

Third baseman Manny Machado also will be activated from the disabled list soon — perhaps as early as the series opener against the Pirates on Tuesday, but almost certainly by the road trip that starts Friday against the Minnesota Twins.

Machado, who is testing his surgically repaired left knee on a minor league rehabilitation assignment, played his third game at High-A Frederick on Sunday. He went 4-for-4 with a walk, two doubles, two RBIs and three runs scored. He was 8-for-12 with four doubles and a triple this weekend for the Keys.

Showalter said there are three possibilities for Machado's next step: He will remain at Frederick and play Monday, go to Triple-A Norfolk to play Monday or take an off day and then rejoin the Orioles on Tuesday.

After Sunday's game, Showalter said the expected plan was for Machado to serve as the designated hitter at Frederick on Monday, but that could change.

"I think the biggest part of that equation is going to be what Manny thinks. I don't call him every day … and ask him," Showalter said. "I think he appreciates the heck out of that. He'll know. We are a lot closer than we were."

At some point, the Orioles will have to make two corresponding roster moves to make room for Machado and Patton this week — assuming they also will fill Davis' open spot Tuesday with someone besides Machado.

One possibility, Showalter confirmed, is to bring up a reliever for one day to provide bullpen depth and then send that player back down Wednesday to make room for Patton. That could be left-hander T.J. McFarland, who was optioned Friday to Norfolk and would normally be prohibited from re-joining the major league club for 10 days after the demotion. But since he would be replacing an injured player — Davis, in this instance — McFarland could return before the waiting period expires.

Another possibility Tuesday is for the Orioles to re-sign first baseman-outfielder Steve Pearce, who was released Sunday, but that one's also complicated.

Ultimately, the easiest moves are for the Orioles to activate Machado and Patton and send one position player — such as recently recalled infielder Jemile Weeks — back to Norfolk.

As Showalter likes to say, "we'll see."

Pearce released; could still return to Orioles

The Orioles put Pearce on unconditional release waivers Sunday, meaning he can be claimed by any major league team in the next 48 hours. The claiming team would have to pick up what's remaining of his $850,000 contract for 2014.

If Pearce, who was designated for assignment Tuesday after going 1-for-7 this season, is not claimed by Tuesday afternoon, he can become a free agent. He then would be eligible to sign with any club. Normally, if a team that released the player re-signs him, he would have to wait 30 days before re-joining the active roster.

However, there's at least one rules scenario that would allow Pearce to re-sign with the Orioles and re-join the club Tuesday, according to an industry source. That could at least partially explain why the club has not filled Davis' roster spot yet.

But there's also no guarantee that the right-handed hitter will go unclaimed. He's a .266 lifetime hitter against left-handers and can play outfield or first base.

Pearce, 31, was designated for assignment last week to make room for McFarland because the Orioles needed an extra reliever for the series against the Toronto Blue Jays. Now the Orioles are juggling their options at first base, with Ryan Flaherty and Nick Markakis subbing in since Davis was injured.

Orioles executive vice president Dan Duquette would not comment on whether the club wants to retain Pearce, saying only that Pearce had been released and his waiver period expires Tuesday.

Davis' strain not considered most severe

Showalter said Davis' left oblique strain, which also could be called a slight tear, is not the "most severe" type of strain, so it is possible that the slugging first baseman can return when eligible May 11. But the manager isn't counting on that return date.

"If you go through the studies through the years, there's three types: low, medium and high. I'm not sure the terminology, but … where they think it is, is not the highest level," Showalter said. "I'm hopeful [of Davis' return] on the 11th. I'm not expecting it. It wouldn't be very smart to think it's a given."

It hasn't been decided where Davis will receive his treatment, but he is lobbying to go on the road with the Orioles at the end of the week.

Around the horn

Markakis has hit in seven straight games and picked up his 1,400th career hit with a ninth-inning single Sunday. He is three behind Al Bumbry for ninth-place on the franchise's all-time hit list. … Right-hander Bud Norris had no problems in his side session Sunday and will start Wednesday against Pittsburgh. He tweaked his right hamstring in his last start Thursday in Toronto. … Norfolk right-hander Kevin Gausman was removed from Saturday's game after throwing 42/3 innings because he had reached his pitch limit of 75. Showalter said the organization is keeping Gausman on a pitch count now to ensure he can help the Orioles late this season and in any possible postseason situation. … Outfielder Delmon Young has started just once in the past eight days, but Showalter said he is healthy and would be in the lineup when the matchup is favorable. Young was just 3-for-14 lifetime against Sunday's starter, James Shields. Young pinch-hit in the ninth inning and doubled against Royals reliever Greg Holland.