Bryce Harper blasts one of his two doubles Wednesday night in the Nationals’ 8-4 win over the Chicago Cubs. (Jonathan Newton/The Washington Post)

Dusty Baker had an inkling. Yes, Stephen Strasburg hadn’t completed a sixth inning in three weeks, and his ERA had jumped three-quarters of a run, but Baker sensed a recovery was looming Wednesday night at Nationals Park. The Chicago Cubs were in town. A unique hum radiated on a temperate evening at the ballpark. It was the homegrown right-hander’s kind of night.

“Stras will have a good one tonight,” Baker prophesied. “He usually does in bigger games, I find. So he’ll be fine.”

Baker was spot-on as top-form Strasburg resurfaced to smother an undermanned Cubs lineup for seven innings in Washington’s 8-4 victory. Not even a back spasm, which arose during the fourth inning, could impede Strasburg from completing a 96-pitch performance, though it was a factor in the Nationals deciding to hand the game off to the bullpen in the eighth inning.

“It was just like sitting down between innings, just kind of felt it mid-back, just kind of get tight,” said Strasburg, who received treatment after the game and insisted the spasm won’t be an issue moving forward. “The first couple throws warming up, going back out there, felt it a little bit. Just tried to mentally not let it affect me. And I think it kind of helped. It slowed everything down a little bit.”

Stephen Strasburg struck out 13, walked one and surrendered four hits over seven innings. (Jonathan Newton/The Washington Post)

Strasburg struck out 13, walked one and surrendered four hits. Two of the three runs he allowed were earned, dropping his ERA to 3.51. Enny Romero then gave up his first earned run in 14 appearances — on a mammoth solo home run to Anthony Rizzo — in the eighth inning, but he recovered, and Matt Albers sealed Washington’s second straight victory with a scoreless ninth.

The efforts didn’t go to waste because the Nationals (47-31) throttled John Lackey early, posting six runs through three innings. The veteran right-hander ended up allowing eight runs across 5⅓ innings. Every Nationals starter except Michael A. Taylor reached base — and Taylor contributed a sacrifice fly. Anthony Rendon fell a triple shy of the cycle and reached base four times. Trea Turner notched two hits and a walk, which he swiftly turned into two bases with his 33rd steal, which is tied for the major league lead and more than 10 teams.

Bryce Harper thumped two doubles, the second of which required some hustle, and spent his evening diving and sliding on the base paths and in right field.

“Bryce was patient,” Baker said. “It seems like he’s getting his act back together. You see him taking pitches and not really going for a lot of the bait.”

Meanwhile, after nearly squandering a five-run lead in the ninth inning of Monday’s series opener, it has been an eventful couple of days for the middling Cubs (39-39) in the District. It began with catcher Miguel Montero criticizing pitcher Jake Arrieta for his inability to hold on base runners after the Nationals stole seven bases off the battery Tuesday. Montero, an established 33-year-old big leaguer, was promptly designated for assignment early Wednesday — around the same time some members of the team, from executives to players and including Manager Joe Maddon, were on a voluntary visit to the White House.

Nationals shortstop Trea Turner leaps to make a throw to retire the Cubs’ Javier Baez in the ninth inning. (Jonathan Newton/The Washington Post)

The whirlwind continued Wednesday beyond the final score, when Kris Bryant rolled his ankle on third base while catching a routine popup in the fifth inning. The reigning NL MVP required assistance to walk off the field and was replaced by Jeimer Candelario.

“Nobody wants to see anybody get hurt,” said Harper, who grew up with Bryant in Las Vegas. “One of the best players in baseball, you want to see him playing every single day.”

Bryant had been one of the few Cubs able to solve Strasburg, who was nearly unhittable over the first three innings. He was unleashing an easy 98-mph fastball from his now standard stretch, dropping hammer curveballs for strikes in any count, and working a crisp change-up off them. Only Bryant figured him out, singling to center field as the game’s second hitter.

Besides that, Strasburg compiled seven strikeouts while throwing eight total balls through three innings. Three of his first seven strikeouts came on three pitches, and he threw a first-pitch strike to nine of the first 10 batters he faced. He was bombarding the strike zone.

“That was as consistent of him throwing strikes as I’ve seen him,” Nationals catcher Matt Wieters said. “And that’s saying something because he throws a lot of strikes.”

At the plate, Strasburg smacked a single off Lackey and scored during Washington’s four-run second inning, which Rendon and Matt Wieters kicked off with the Nationals’ seventh set of back-to-back home runs. Strasburg was in complete control.

But his governance was interrupted in the fourth inning when his pinpoint command quivered just enough for the Cubs to capitalize. Bryant was the thorn again, clubbing a double to begin the inning.

Two batters later, Strasburg fell behind Willson Contreras 2-0 and hung a curveball that Contreras skied into the left field seats for a two-run home run. Chicago added a third run in the fifth inning, when Albert Almora Jr. laced a leadoff double and scored on Ryan Zimmerman’s ninth error at first base as Strasburg’s back became a nuisance.

The Cubs’ fortunes flipped again, however, in the bottom of the frame. First, Daniel Murphy smacked his 14th home run. Then Bryant rolled his ankle on third base. Strasburg was already amid retiring the final eight batters he faced, striking out four of them, pitching through the back trouble to end the dominant night his manager felt coming all along.

“He gave us all he had in the time he was out there,” Baker said. “Then our bullpen did the rest.”