The Orioles outdueled the Nationals and starter Gio Gonzalez on Thursday night, a game in which both teams entered in first place in their respective divisions. (Toni L. Sandys/The Washington Post)

— For the first time in major league history Thursday night, teams from Washington and Baltimore faced each other with both clubs beginning the night all alone in first place.

Normally, that might qualify as a pleasant curiosity, a nice summer treat for fans of two franchises 38 miles apart, including some who root for both. The takeaway from the night might be that the Orioles beat the Nationals and Gio Gonzalez, 4-3, a win that gave Baltimore two-games-to-one bragging rights in this beltway battle.

However, given the happenings of the past few weeks, that’s probably thinking too small. Roughly 60 percent of the way into their schedules, the seasons of the Nationals and Orioles are not playing out as mere pleasantries. The road signs in front of both say “Opportunity.”

As slumps or injuries to rivals mount, and as their own ability to heal or find internal solutions for their problems increase, one of these teams seems set for an October run.

Both? Dream if you want.

Two years ago both teams made the playoffs, but neither was ready to advance. The Nats were raw and nervous, the O’s almost shocked at their own improvement. In 2012, during a slump, Manager Buck Showalter even got a laugh by telling his Orioles the exact costs of his two children’s college educ ations. “You gotta pick it up for me, guys,” he recalled saying. “You’re playin’ for the tuitions.”

Both teams have matured. But the odds against the O’s and Nats meeting in the World Series this year are large. However, for the first time, you can talk about it without the sarcasm. And you can wonder what pieces would need to fall in place to bring about something more modest, but still dazzling — like both teams reaching their league championship series.

“These are two seriously competitive teams, capable of winning 90 or more games,” Orioles General Manager Dan Duquette said. “And we’ve seen plenty of teams in the Series with 90 or less.”

“The Nationals look great to me,” Showalter said. “Everybody knows their starting rotation but they’ve got three relievers with ERA’s in the 1’s. They can catch the ball, probably have three Gold Glove caliber fielders.”

The Orioles can be gracious. They’ve dominated the head-to-head series, 20-11, the past six years. In this series, they won a one-run game and an extra-inning game, both characteristics of a well-managed fundamentally alert team. Baltimore has a 16-13 mark in one-run games and 8-3 record in extra innings to the Nats’ 11-14 and 2-8.

If one team has lessons to learn from the other, it’s probably the Nats from the O’s. Thursday’s game was decided by an unearned run on a ground ball to shortstop when Ian Desmond, who probably had a (close) play at first base to end the inning but instead chose “an instinct play,” spun and threw to third base trying to trap an Oriole rounding the bag. The throw hit the box seats.

Though the Nats, still percentage points ahead of Atlanta, are in good shape, it’s the Birds who are sitting prettiest right now, leading Toronto by three games in the AL East.

Already this week, the Yankees have put their ace Masahiro Tanaka on the disabled list with a partially torn ulnar collateral ligament in his elbow and also announced that CC Sabathia may not return this season. On Wednesday, the Red Sox started five rookies and released catcher A.J. Pierzynski, neither of which can be viewed as a positive sign for the defending champs. The Rays, 42-52, are so far back they may trade ace David Price.

The second-place Blue Jays mirror the Orioles — Toronto leads the AL in homers, the Orioles are second — and each has a second-tier pitching staff. However, Baltimore is making pitching progress with fireballing Kevin Gausman now apparently ready for a full-time rotation spot after the all-star break. Lefty Zach Britton, recently a flop as a starter, is now a shutdown closer who touches 98.

Show Duquette and Showalter a mess and they neaten it without spending a dollar. Last night, farmhand Caleb Joseph caught and super sub Steve Pearce homered. “Our players know we aren’t going to go out and spend big money to fix every problem,” Showalter said. “That creates good morale because they know we’re committed to building from within.”

While the rest of the AL East disintegrates, the O’s have patched together a credible catching tandem to replace injured Matt Wieters; Chris Davis emerged from a slump with an 11th-inning, game-winning homer in Washington. Perhaps most important, Manny Machado finally looks like his 2013 self again. Duquette explains that his torn patellar tendon injury was “so significant” that it required part of a hamstring to be used as a transplant. Machado even had to learn an altered running stride. An 8-for-9 hail of hits to start the Nats series has calmed any Manny fears left in B’more.

Despite losing a one-run and an extra-inning game to the O’s, the Nats have been one of baseball’s hotter teams for six weeks at 24-14. And they finally appear to be at full health, Thursday night’s Desmond scare notwithstanding. Of three injured sluggers, all in cold power slumps while recovering from hand or wrist injuries, two may be coming out of hibernation. Wilson Ramos homered on Wednesday and Ryan Zimmerman ripped an RBI single and long double on Thursday. Bryce Harper may thaw next.

While the Nats have survived their massive injuries, other teams must now pass their tests. On Thursday, the team the Nats seldom beat, the Cards, lost their catcher and leader Yadier Molina for up to three months with a torn right thumb tendon; the Reds’ star second baseman Brandon Phillips needs thumb surgery, too. The Giants are in a 10-20 freefall and the spring-surprise Brewers are plummeting.

Fans of franchises in two-team markets like New York, Chicago or Los Angeles, or teams like the Giants and A’s, often dream about the borderline fantasy that their clubs will meet in the World Series. It’s rare. Yet there have been 18 World Series between such near neighbors.

In March Madness, college basketball teams sometimes watch in wonder as their “bracket opens up.” The higher- seeded teams lose or get injuries and then the unexpected or unbelievable happens. In the AL East and NL East, have the Orioles and Nationals suddenly found themselves in “busted brackets?”

And if so, where will it lead?