Nationals shortstop Ian Desmond connects for a two run home run, but it's not enough as Washington falls to Arizona. (Katherine Frey/THE WASHINGTON POST)

The Washington Nationals threatened to extend a winning streak Thursday night, but instead were party to a peculiar jumble of events. The Nationals received seven dominant innings from their under-supported ace, a safety squeeze bunt beat them in the 11th inning, Manager Davey Johnson campaigned for Bryce Harper’s expedited return and, as storm clouds approached, the stadium caught fire. Their practice of hovering around .500 remains stuck on repeat, but at least the Nationals vary the plot.

The Arizona Diamondbacks outlasted the Nationals in a 3-2, 11-inning teeth-gnasher at Nationals Park, which started 62 minutes late after a rain delay. Unbeaten left-hander Patrick Corbin and Nationals ace Stephen Strasburg battled to a draw for seven innings. In the 11th, Craig Stammen yielded a leadoff ground-rule double, and two batters later Didi Gregorius pushed across the winning run with a clinical bunt.

The Nationals could not complete their first series sweep since April 11, and they departed for a weekend series in New York at 39-39, ending a day at .500 for the ninth time this month. The Nationals have played better of late, but they have still vacillated between two games below .500 and two games above since May 19.

“We haven’t gotten on one of those streaks we had at the start of [last] year and a couple times during the year, so we’re still waiting for that to happen,” Strasburg said. “But all we can do is give it everything we got every single day, and if we lose, just try to get the next one.”

Johnson offered one possible solution for the Nationals to get unstuck. The Nationals planned for Harper to take Friday off after taking five at-bats in six innings Thursday night for Class AA Harrisburg, rehabbing his bursitis-addled left knee. Saturday was to be his final rehab game, and then he would return Monday.

By the time the Nationals’ loss ended Thursday night, Harper had already beaten out a triple and scored from first on an extra-base hit, sliding home on his knee. Upon hearing Harper’s progress, Johnson perked up and floated the idea of Harper playing Saturday not in Bowie, but in New York against the Mets.

“I’ll take him whenever he’s ready,” Johnson said. “I need to talk to him, see how he’s feeling. I’d like to have him in there. He can’t be hurting too bad.”

In the middle of the 11th inning, the space behind a light bulb in the bank of lights high above the first base line caught fire. Security personnel vacated fans from sections 236 through 224. A thin cloud of smoke billowed. Players could hear the light crackle and pop.

Immediately following the game, the Nationals were still trying to determine what exactly caused the fire, Lerner Sports COO Alan Gottleib said. The Nationals were able to quickly “stabilize” the situation, Gottleib said, and no one was hurt.

As the game continued below, Adam LaRoche ripped a one-out single to center field. Ian Desmond, the next batter, grounded to second against Diamondbacks closer Heath Bell. Roger Bernadina popped out to end it.

Stammen had entered in the top of the 11th inning, after Johnson had already used closer Rafael Soriano in the 10th. Miguel Montero blasted a ground-rule double to center field. Cody Ross bunted pinch runner A.J. Pollock to third, and with one out Stammen pitched around Jason Kubel to set up a possible double play.

Gregorius ensured that wouldn’t happen. With the count at 2-1, he deadened a perfect bunt down the first base line. Pollock had not been running with the pitch, but as he saw the ball trickle away from the plate, he sprinted home without contest. Catcher Jhonatan Solano’s quick throw to first was not in time.

“When that play is executed right, it’s pretty much unstoppable,” third baseman Ryan Zimmerman said. “The way he put the bunt down right there, nobody was going to get that guy.”

Strasburg cruised for five innings, including an eight-pitch first. He allowed three hits and walked one. Ian Desmond bashed his 13th homer of the year in the fourth inning, smashing Corbin’s 2-2 slider into the left field bullpen to give the Nationals a 2-0 lead. The Nationals could be forgiven for not scoring again off Corbin, who ranks fourth in the NL with a 2.22 ERA.

Strasburg appeared ready to make it hold up, but in the sixth, he ran headlong into turbulence.

Corbin, hitting .121, whacked a single into left field. Gerrardo Parra ran into a ball that he had bunted, which gave Strasburg one out. Aaron Hill then blasted a 1-0 fastball into the left field bullpen, next to some celebrating Arizona relievers. Hill had been a pest all series, and now he had tied the score, 2-2.

Strasburg escaped the inning without further damage. But after a single, a walk and a visit from pitching coach Steve McCatty, his pitch count rose to 102. Johnson faced a decision.

Because of a brief stay on the disabled list and the Nationals’ careful handling since he returned, Strasburg had not thrown more than 95 pitches since May 26. After the Nationals pulled Strasburg from his last start, he said, “I’m not a kid anymore.” He wants to stay out there. And Thursday, Johnson let him.

“I’m kind of past going six innings,” Strasburg said. “I want to get used to going seven, eight or hopefully nine someday. But, yeah, I was definitely happy with that.”

Strasburg carved through the bottom of the Diamondbacks’ order in 11 pitches, buckling Corbin with a change-up for his fourth strikeout with his 113th and final pitch.

Strasburg left with the score tied, again with little run support. The Nationals have averaged 2.7 runs in games he started, the fewest of any starter in the majors. Strasburg’s ERA settled at 2.41, and his record stayed 4-6.

“It’s making me a better pitcher,” Strasburg said. “I’ve learned a lot already. The one thing I’ve learned is, you can’t go out and try to do too much. You can’t go out there and try to pitch to the scoreboard. Once you do that, you’re done.”

Strasburg kept the Nationals in the game, and scoreless relief innings from Ian Krol, Drew Storen and Rafael Soriano gave the Nationals’ offense more chances. They had won a series, at least, but they’ll head to New York still trying to separate themselves from treading water.