That's a rare phenomenon for both teams, as neither has finished with a winning record in the last seven years. The Orioles go back even farther than that, and Washington hasn't had a winning record since the franchise's final year as the Montreal Expos. Fittingly, this series has been close, with the O's owning a 16-14 edge since the start of 2006.
Baltimore has lost the season series to Washington once since the latter team's relocation, but the two geographic rivals have managed to take a 3-3 split twice in the last five years. The Orioles and Nationals may both look at Interleague Play as a chance to escape a contentious division, an aspect of the schedule endorsed by utility player Jerry Hairston Jr.
"I like Interleague Play," said Hairston, a former Oriole. "It definitely breaks up the monotony of a long season. It gives the fans an opportunity to see different teams they don't normally see at their ballpark or on the road."
The Orioles won only one series last year during Interleague Play -- a sweep over Washington at Camden Yards -- and finished with a 7-11 record against National League opponents. Baltimore is just 108-138 all time during Interleague Play and has managed a 60-62 record against NL teams at Camden Yards.
Baltimore will play Washington twice -- once at home and once on the road -- and will also face off against Pittsburgh and potential postseason contenders Cincinnati, St. Louis and Atlanta during this portion of the schedule. The Nationals, meanwhile, will play one fewer series, matching up against the Mariners, White Sox and Angels in Interleague Play.
The Orioles will have the benefit of the designated hitter over the next few days, but they'll have to outpitch the Nationals to beat them. Baltimore will throw Jake Arrieta, Jeremy Guthrie and Chris Tillman at Washington this weekend, and the Nats will counter with veteran Jason Marquis, lefty John Lannan and youngster Jordan Zimmermann in the finale.
Nationals: Marquis lends consistency to rotation
Marquis has led the Nationals to wins in five of his last six starts, and he's managed to complete at least six innings in all but one of his outings this season. The right-hander has yet to allow more than one home run in any of his starts and he's given up more than three earned runs just once. Marquis won his last start thanks to a six-run cushion in the first inning.
"[It] allowed me some room for error with my mistakes," Marquis said of his team's run support in his last outing, an 8-4 victory over the Marlins. "The defense did a great job. It was a good team effort."
Orioles: Arrieta in a groove
Arrieta has begun to establish himself. The former fifth-round Draft pick has won four straight decisions and hasn't lost since April 9, his lone outing this season in which he allowed more than three earned runs. Removing that start -- an outing in which he gave up eight earned runs -- from his record gives Arrieta a 2.81 ERA.
First baseman Derrek Lee (left oblique strain) and second baseman Brian Roberts (concussion-like symptoms) were put on the disabled list on Thursday, although because of Roberts' injury, the Orioles were able to place him on the newly enacted seven-day DL rather than the 15-day DL.
"Any time you're dealing with a concussion and heads and stuff, you're concerned about it," manager Buck Showalter said of Roberts, who was limited to just 59 games last year due to a herniated disc in his lower back. "I was talking to Brian. This isn't anything like the symptoms he was feeling last year. That's good, but you still have those symptoms that we're going to make sure that we have our arms around before we go forward."
The O's recalled left-hander Troy Patton and righty Chris Jakubauskas from Triple-A Norfolk to take the roster spots of Lee and Roberts, although both were demoted after Thursday's 13-2 loss to the Yankees.
Twenty-eight of Washington's first 42 games came against teams with a winning record. None of its next nine games will be against an opponent with a winning record.
The Nationals are 11-18 against NL East rivals this season, but they'll play such teams in just four of their next 48 games.
Former Orioles star and Hall of Famer Brooks Robinson turned 74 on Thursday.
The Orioles didn't reach 20 victories last year until June 24. Baltimore didn't have 11 home wins until June 10.