WASHINGTON -- This is why Major League Baseball moved back to the Nation's Capital: Meaningful games, even in May.

"It's better than the alternative," Orioles manager Buck Showalter said before Nick Markakis hit an 11th inning homer and the Orioles won Friday night's Battle of the Beltways, 2-1, at Nationals Park.

The alternative was no baseball here at all.

That was the case from 1972 -- when the expansion Senators left for Texas -- to 2005, the year the Expos moved from Montreal and were renamed the Nationals. To understand the depth of despair among long-suffering local fans, there hasn't been a postseason game played in the shadow of the Capitol building since the original Senators lost Game 5 of the 1933 World Series to the New York Giants on Oct. 7 of that season, nearly 79 years ago.

Thus, the opener of a three-game Interleague series between the first-place Orioles and second-place Nationals on Friday night offered a much needed shot of adrenalin for the crowd of 36,680 that was liberally sprinkled with Orioles orange among a sea of Nats red. Nearly 5,300 of those ticket buyers walked up to the windows on Friday night, revealing a budding excitement that the players obviously noticed.

"It was an electric atmosphere, a great atmosphere to play in," said Orioles starter Jake Arrieta, who pitched seven innings of one-run, six-hit ball and had nine strikeouts. "It's two great ballclubs, two young ballclubs. Both clubs are [at the top] of their divisions. It's going to be a battle the next two games. With the type of pitching these clubs have, they're going to be close games. It's going to be an exciting weekend."

To be clear, until now, there never has been a heated Baltimore-Washington baseball rivalry, even when the two cities were members of the American League. The Orioles moved from St. Louis to Baltimore in 1954 -- changing their name from the Browns to the Orioles in the process -- during the dying days of the first Senators franchise. That team skipped town to Minnesota in 1961 and was replaced by its expansion namesake. By the time the Orioles were good, winning the 1966 World Series in four straight over the Dodgers, the Twins had four winning seasons, including an AL pennant in 1965, losing to those same Dodgers in the World Series.

Their sorry Washington replacements had one .500 season in 11 years before vacating town again.

Even in the most recent era, heading into Friday night, the Orioles had a 19-17 edge in the 36 Interleague games played between them and the Nationals since the rivalry resumed in 2006. But not one of them had any meaning. The Nationals have been rebuilding and retrenching since leaving Montreal, where their only trip to the playoffs was a National League Championship Series loss to the Dodgers in 1981.

The Orioles haven't been to the postseason since losing the 1997 ALCS to the Indians. To illustrate how long that's been, current Nationals manager Davey Johnson was then the Baltimore skipper.

That's a lot of down years for both clubs.

Johnson was the second baseman when the Orioles won their first World Series in 1966, around the time he and a teammate rescued Frank Robinson from the bottom of a pool. The superstar and now Hall of Fame outfielder couldn't swim. But along with Hall of Fame third baseman Brooks Robinson, Frank was the heart of that team.

"We don't know why he went into the pool, but we were not going to let him drown," said Johnson, who went into the drink with catcher Andy Etchebarren.

Johnson professes to still have a soft spot for the Orioles.

"I love coming back and playing Baltimore," said Johnson, who's managing his first Interleague series against the Orioles. "I spent so much time with them as a player and a manager. I mean, I picked them when I could've signed with any other team. I've always followed the Orioles and whatever's going on with them ever since I was a teenager. That's a long time.

"I'm real happy they're playing great and are at the top of their division. [The AL East] is a tough division. We go back into our division when we finish up with them. So I think it's only perfect that we tune up on the Orioles."

That tuneup will have to wait at least a night. The Orioles, at 26-14, played their eighth extra-inning game of the season and won one of them on the road for the sixth consecutive time. Their 14-5 overall road record right now is the best in the Major Leagues.

They lead Tampa Bay by two games, the Yankees by 4 1/2 and the last-place Red Sox by 7 1/2. Who would have thunk it? The net result is that nascent Orioles fans are now coming back out of the woodwork as those that made the 45-mile trip south from Baltimore on Friday night attest. And if the trend continues during the 20th anniversary season of Camden Yards, perhaps it won't be so easy for the Yankees and Red Sox faithful to scoop up tickets in Baltimore's home yard.

No question, when the Markakis bolt struck the facade of the second deck in right field, there was a din of Orioles good cheer in the four-year-old ballpark. This is all new to the current generation of Washington baseball fans. For their Baltimore brethren, call it an awakening.

"We definitely took notice of that," Markakis said. "It was just great. It was great to see the fans out there. It was a good ballgame between two great clubs and a terrific ending."

Round 2 is Saturday night.