Lough took Johnson's second pitch of the night, a 1-0 two-seam fastball clocked at 95 mph, into the right-field seats to give the Orioles a 6-1 lead.
Earlier, the Orioles scored three runs off Gray in the bottom of the fifth inning to take a 4-1 lead, capped by two-out, run-scoring singles by Nick Markakis and Adam Jones.
Rookie catcher Caleb Joseph opened the rally with a double into the right-center-field gap. Joseph sat on a 3-2 curveball and slapped it the other way, scoring David Lough from first base.
The 27-year-old Joseph, who has found himself in the starting lineup more often with starter Matt Wieters on the DL, entered the game 5-for-41 before recording his second big league RBI with his fifth-inning hit.
Two batters later, Markakis slapped a 1-2 pitch past the left side of the infield to score Joseph. He moved to second on a walk to Manny Machado, then scored on Jones' RBI single up the middle.
Jones gave the Orioles an early lead in the first inning, taking a 3-1 fastball over the center-field fence for a solo homer.
In the third, after getting ahead of center fielder Coco Crisp 0-2, Gausman threw a 97-mph fastball over the heart of the plate that Crisp turned on and sent into the flag court in right field.
But that was the only run Gausman allowed. He would allow just two hits — the back-to-back singles to open the sixth — over his final 4 1/3 innings.
“He's getting the opportunity,” Jones said. “This game is all about confidence. It's not about necessarily about stuff. … Now he's going to get his shot to start. I told him: ‘Hey, go after him. Use your stuff. You've got a good arm for a reason, so use your stuff and go after them.' "
With two on and one out in the eighth, right-hander Darren O'Day yielded a two-run single to pinch hitter Kyle Blanks, but recovered to strike out Donaldson and Moss to end the inning. He added a scoreless ninth to close out the game.