BALTIMORE -- In a matchup between the two top teams in the American League East, a rookie right-hander got the best of a 35-year-old looking for his major league-leading 11th win.
Nick Markakis had two hits and an RBI for the Orioles, who moved within 3 1/2 games of first-place Toronto.
Gausman (2-1) allowed five hits, walked three and struck out three in his second consecutive solid outing. The 2012 first-round draft pick stymied Oakland on June 7 after being recalled from Triple-A Norfolk and now appears to be a fixture in the starting rotation.
"He's done what it takes to be considered," Orioles manager Buck Showalter said. "He's taking care of his end of it."
Gausman, 23, has given up only two runs in 13 innings during his latest stint with Baltimore.
"I feel good about what I've done. I feel comfortable right now," Gausman said. "Whatever happens is going to be for the club's best interest."
Zach Britton worked the ninth for his sixth save. The victory wasn't secured, however, until a replay review confirmed the final out on a double-play grounder.
Buehrle (10-3) yielded four runs and eight hits in 6 1/3 innings to lose his second straight start following a six-game winning streak. The left-hander allowed three runs or fewer in 12 of his previous 13 starts.
"I feel like there were times I made a lot of mistakes, and they made me pay for them," Buehrle said. "And I made a few good pitches, and they put the ball in play and got some base hits."
Toronto has lost three straight and five of six, scoring only four runs in those five defeats.
"As hot as we were, we were going to cool off sooner or later," manager John Gibbons said. "We'll get it going. We're too good of an offense. We'll be OK."
Baltimore needed just two at-bats to take a 2-0 lead. Markakis led off with a single, and the seldom-used Young sent a changeup into the seats in left field, his first home run since April 8 and only the fourth against Buehrle this season.
It was the eighth straight game in which Toronto allowed the opposition to score first. In those games, the Blue Jays have been outscored 16-4 in the first three innings.
"It seems like we've gone out as starting pitchers and given up runs in the first inning," Buehrle said. "When your offense is struggling to score runs ... it kind of seems it's taking the wind right out of our sails. We got to do a better job going out there and throwing up zeroes."
Toronto got a run in the fifth when Juan Francisco doubled and came home on a single by Melky Cabrera. The double ended Baltimore's string of 23 innings without allowing an extra-base hit, and the run snapped the Orioles' streak of 19 consecutive scoreless innings.
That would be the only flaw in an otherwise solid performance by Gausman, who was 0-1 with a 6.14 ERA in his previous four appearances against Toronto.
"Gausman was good tonight," Gibbons said. "He's got that overpowering fastball. He was keeping it in the zone. I think in the past he's had some control issues, but it's all coming together for him."
Doubles by Jonathan Schoop and Markakis put Baltimore up 4-1 in the seventh, and Toronto got a run off Ryan Webb in the eighth when Jose Bautista doubled, stole third and scored on a groundout by Adam Lind.
Toronto OF Colby Rasmus (right hamstring) went 1-for-3 in his first rehab start Thursday, serving as designated hitter for Triple-A Buffalo. ... Baltimore will send Ubaldo Jimenez (2-7) to the mound Friday night in the second game of the series. Jimenez is 0-5 with a 7.04 ERA in six home starts. Drew Hutchison (4-4) will start for Toronto. ... Baltimore pitchers have gone 42 straight innings without allowing a home run. ... Toronto's Jose Reyes opened the game with a single to extend his hitting streak to 13 games. ... Markakis passed Brian Roberts and moved into sole possession of seventh place on the Orioles' career list with 1,453 hits.