The Orioles were forced to call on pitching prospect Kevin Gausman for a spot start Saturday night against the Oakland Athletics because of an injury to their rotation. With his honeymoon of hype over, all the hoopla that accompanied the 23-year-old's previous starts was gone. This was about filling a need.

Gausman responded by providing the Orioles with the best start of his major league career and an encouraging glimpse of the flame-throwing right-hander's immense potential.

Gausman held an A's team with the American League's best record to just one run over a career-high seven innings in a 6-3 victory. The Orioles hit two homers, including David Lough's two-run shot off former closer Jim Johnson, who was making his first appearance at Camden Yards since being traded in December.

The win, before an announced sellout crowd of 44,202 on Manny Machado Bobblehead Night, was Gausman's first as a starter. He earned each of his three major league wins last year working out of the bullpen.

An Orioles rotation that has been up and down this season and that lost top insurance policy Johan Santana to a season-ending Achilles tendon injury Friday received a jolt from Gausman, who was called up from Triple-A Norfolk when right-hander Miguel Gonzalez went on the disabled list Friday.

“It was like, ‘The club has a need, and that's why I'm coming,'“ Orioles manager Buck Showalter said. “It was a different atmosphere … different circumstances. I don't think it was like he felt like he was the guy that everybody was counting on to be perfect tonight, but we really needed those six or seven innings tonight.”

Gausman (1-1) allowed four hits, struck out six and issued one walk against an Oakland team that entered the night leading the AL in on-base percentage and walks drawn.

“Give them walks, they can hit, but he made them throw strikes, and he went after them,” Orioles center fielder Adam Jones, who drove in two runs and hit his ninth homer of the season, said of Gausman. “That's all you ask out of your starters: Go after the hitters and let your defense.”

The organization has handled Gausman (1-1) with care this season, holding him to strict pitch limits to ensure his availability down the stretch. But on Saturday night, the Orioles removed their restrictions to get a much-needed win.

Gausman threw 102 pitches, the most he has thrown in seven big league starts and more than he's thrown in 11 Triple-A starts this season.

“He went to another level there and wasn't going to give in,” Showalter said. “I know going into the game, the most he had pitched this year was 61/3, and I think 93, 94 pitches, so I wanted to take him about 10 more.”

No pitch was more important than the 99-mph fastball Gausman whizzed by Oakland cleanup hitter Brandon Moss with two runners in scoring position and the tying run at the plate in the sixth inning.

“When I got in a little bit of a jam in the sixth, I kind of went back to when I pitched out of the bullpen last year,” Gausman said. “Guys on second and third, one out — that's when you've got to bring your ‘A' game. I think pitching out of the bullpen last year helped me to dig deep and just kind of get my best stuff right there.”

Leading 4-1, Gausman allowed back-to-back singles to open the sixth. After a lineout to third by John Jaso, both runners moved into scoring position after Gausman uncorked a wild pitch.

He fed Josh Donaldson four straight high-90s fastballs, then, two pitches later, forced him to swing through an 85-mph split-finger fastball.

He needed just three pitches to strike out Moss to end the inning, and walked off the field to a loud ovation.

With Donaldson, “that's exactly what I was trying to do,” Gausman said of mixing his pitches. “It's a pitch he really hadn't seen up to that point throughout the game, so I threw my best split right there and then threw my best fastball to Moss.”

He outpitched fellow first-round draft pick Sonny Gray, who entered the night fifth in the AL in ERA (2.45) and eighth in opponents' batting average (.224).

The Orioles (31-29) scored five runs off Gray, the most he's allowed this season, over a season-low 5 1/3 innings.

Gray left with one on and no outs in the sixth inning as Johnson — a former Orioles draft pick and All-Star who recorded back-to-back 50-save seasons with the club before being traded to Oakland (38-24) — entered the game.