WASHINGTON -- The MRI performed on Jeremy Guthrie's upper back on Friday is clean, and the Orioles remain cautiously optimistic that their ace can avoid a trip to the disabled list.

"This was about as good [news] as one could have hoped," Andy MacPhail, president of baseball operations, said of Guthrie, who was ruled to have a minor muscle strain. "He's still in line potentially -- no sure thing -- to make his next start [on Tuesday]. So we will just see how it responds in the next two days."

For now Guthrie is day-to-day, and he told manager Buck Showalter that the area was more sore than tender on Friday morning, which is a good sign.

The right-hander was lifted from Thursday's game in Toronto after five innings with back discomfort, an alarming development given how much he prides himself on his conditioning and ability to go deep into the games.

Asked if there's a possibility that the team will push back Guthrie's start to give him another day or two -- while still keeping him off the DL -- Showalter didn't rule it out.

"With the off-days, we could," Showalter said, referring to Thursday's day of rest following the team's nine-game road trip. "We're obviously going to need a starter on Tuesday. Immediately, somebody that is here who is capable of doing it is [Jason] Berken. But that means that you have to stay away from him [in relief]. I think it's kind of a work in progress to see what the needs are as far as Berken is concerned. Andy's got it wired about some things that we could do as early as [Saturday] if we have to. But we have to get ... a feel for where Jeremy is."

If the Orioles do turn to Triple-A Norfolk for another arm, starter Brad Bergesen -- who made the team as a long reliever/extra starter out of camp -- is a top candidate, as is right-hander Mitch Atkins. The two are scheduled to throw for the Tides on Sunday and Monday, respectively, and could join the Orioles' bullpen even if Guthrie is able to make his next start.

That would be ideal for an Orioles rotation that has struggled to consistently go deep in games. Guthrie is coming off consecutive seasons of 200-plus innings and has been a mainstay atop a youth-infused rotation. He is 2-8 with a 3.56 ERA in 15 starts, throwing a team-leading 91 innings.

Britton notches first big league hit and RBI

WASHINGTON -- Rookie Zach Britton recorded his first Major League hit and RBI on Friday night, doubling to left-center to score Robert Andino as part of a two-run fourth inning.

The 23-year-old Britton, who grounded out in his first chance against Nationals starter Jason Marquis, connected on a 1-0 sinker with two outs.

Derrek Lee scored the first run of the inning, belting a one-out double into center and coming home on Andino's base hit to left field.

"It was fun," Britton said of the experience. "I think I was more happy because there was a guy on base, two outs, and I was able to get him in. And as a pitcher, that helps you, gets you a little bit of a cushion. I was pretty excited running the bases."

Vladdy a bench player during Interleague Play

WASHINGTON -- Manager Buck Showalter wasn't willing to tip his hand one way or the other, but it's likely that designated hitter Vladimir Guerrero will be solely a pinch-hitter as the team plays six consecutive games in National League parks, beginning on Friday.

Guerrero saw action as a pinch-hitter in Friday's 8-4 loss, batting for starter Zach Britton in the sixth inning and connecting on an RBI single.

As for using Guerrero in the outfield, "I wouldn't rule it out completely," Showalter said. "Obviously, I talked to Vladdy about it."

Guerrero, who was adamant about doing work in the outfield this spring, entered Friday having played in 63 of the team's first 66 games, so Showalter said the six-game stretch could be a nice "refresher" in giving the slugger time to recharge.

"I'm not going to paint ourselves in a corner on what we're going to do and we're not going to do," Showalter said. "He's taken some work [in the outfield] since Spring Training every day in some form or fashion. A lot of people forget how good of an outfielder he was at one point in his career, but I also want to make sure I don't put him in a position with something that he's not able to do."

Without Guerrero at cleanup, Showalter moved catcher Matt Wieters to the No. 4 spot on Friday night.

Orioles make a number of roster moves

WASHINGTON -- The Orioles made a pair of roster moves following Friday's 8-4 loss to the Nationals, designating right-hander Jeremy Accardo for assignment and optioning infielder Ryan Adams to Triple-A Norfolk, with right-hander Brad Bergesen and infielder Blake Davis joining the team in their place.

Bergesen made the team as an Opening Day swingman/extra starter, while Davis' contract was purchased by the Orioles, and he will be added to the team's 40-man roster with the extra spot.

Accardo allowed three earned runs and recorded just one out on Friday, immediately surrendering a lead after allowing a five-pitch walk to Wilson Ramos and an RBI double to Jerry Hairston to start the bottom of the sixth.

It was the fifth time in six outings that Accardo has given up a run. He allowed 55 baserunners in 32 1/3 innings, giving up 37 hits and 17 walks and hitting a batter along the way.

Bergesen went 2-1 with a 1.64 ERA in three starts for the Tides after being optioned on May 28. He went 1-6 with a 5.36 ERA in 10 outings (nine starts) for the Orioles earlier this season and will likely be used as a long man in the bullpen and a candidate to start on Tuesday if Jeremy Guthrie (sore back) can't go.

Davis' arrival will help Adams -- who started just six games -- continue to develop and get more playing time at Norfolk, which is what the organization has wanted to do for a while. The 27-year-old Davis was hitting .284 with five homers and 24 RBIs in 49 games for Norfolk and will add some versatility given that he can play shortstop, second base and outfield.

Orioles piecing together plan for bullpen coach

WASHINGTON -- The Orioles will stick with their current coach staff until at least Thursday, when they will likely use the off-day to formulate a more concrete plan on filling the role of bullpen coach.

"We might have some different people that come in and come out," Andy MacPhail, president of baseball operations, said of the position, which was vacated when Rick Adair became pitching coach following Mark Connor's resignation on Tuesday.

"We are going to try to be as minimally disruptive to our player-development system as we can be," MacPhail said. "It's unlikely that a guy would come from the Minor Leagues and stay here for three months if we think that that is going to adversely impact the development of some of our kids."

For now the team will continue to use former hitting coach Terry Crowley -- who was an organizational offensive consultant this season -- in the bullpen while it finishes its three-city, nine-game road trip.

"We're fortunate to have him," manager Buck Showalter said of Crowley. "We'll look at it again after the trip to see if there's anything that we want to do, and also get Terry's thoughts on it."