TORONTO -- As major league debuts go, it was pretty good for Baltimore Orioles right-hander Kevin Gausman, but not quite good enough.
The 22-year-old pitched just well enough to lose, allowing seven hits and four runs in five innings, and the Toronto Blue Jays opened the four-game series with a 12-6 victory Thursday night.
Edwin Encarnacion hit his fifth career grand slam in the sixth inning against reliever Pedro Strop to break open the game.
"He gave us a chance to win against a team swinging the bat as hot as anybody," Orioles manager Buck Showalter said of Gausman. "I thought he handled himself the way you'd like to see a young pitcher handle himself."
Gausman (0-1) was promoted from Double-A Bowie for the start.
"Definitely a learning experience for me, but it was awesome," Gausman said. "It was everything I could have imagined and more."
Blue Jays catcher J.P. Arencibia hit a two-run homer against Gausman in the fifth inning to give Toronto a 4-3 lead.
"We were able to have some good at-bats," said Arencibia, who had four RBIs. "Their starter has some pretty good stuff and throws hard. You get up there and you don't know what to expect. You know what he throws, but until you've seen it in person and see the action and how it comes out of his hand, there's a lot of things you've got to incorporate. The second time around, it was a little more comfortable."
Toronto right-hander Brandon Morrow (2-3) gave up 10 hits, including home runs by Chris Davis, Nick Markakis and Adam Jones, six runs and one walk in seven-plus innings. He struck out five.
"He was good," Arencibia said of Morrow. "He left some balls up, but he did a good job. The runs he gave up are definitely not a good showing of the performance he had out there."
Blue Jays manager John Gibbons said of Morrow, "He kept us in there. I think later in the game we had a couple of long half-innings, and I think they took their toll on him."
Left-hander Troy Patton took over for Gausman in the sixth.
Patton's first batter, Colby Rasmus, had his foul down the left field line caught spectacularly by Nate McLouth, who tumbled into seats. After McLouth returned to the field, what appeared to be a beverage container was thrown in his direction from the stands but did not hit him. The game was halted briefly as manager Buck Showalter went out to check on his player.
"It's unfortunate," Showalter said. "The umpires and the security did what they do. Unfortunately it happens in ballparks now and then. Usually it's one person. You don't group the whole."
After the McLouth catch, the Blue Jays loaded the bases with two outs on two walks by Patton and one by Strop. Encarnacion hit a grand slam off the pole in left, his 13th homer of the season, to give the Blue Jays an 8-3 lead.
The Orioles scored in the seventh on a double by J.J. Hardy and a sacrifice fly by Alexi Casilla. Markakis hit his fifth homer of the season on the first pitch of the eighth from Morrow, and Jones followed with his seventh of the year before left-hander Brett Cecil took over. Cecil retired all three batters he faced.
"Cecil has been lights out," Gibbons said.
The Blue Jays tacked on four runs in the eighth.
The Orioles took a 2-0 lead in the third on singles by Chris Dickerson and McLouth and a double by Manny Machado, who had three hits on the night.
Davis hit the first pitch of the fourth off the right field foul pole for his league-leading 15th home run of the season.
The Blue Jays cut the lead to 3-2 with two runs in the bottom of the fourth. Lind and Arencibia opened the inning with doubles to score one. Lawrie beat out a bunt down the first base line, leaving runners at the corners. Rasmus walked to load the bases before Emilio Bonifacio hit a sacrifice fly to the warning track in center for the second run.
The Blue Jays took a 4-3 lead in the fifth on Arencibia's 11th homer of the season. After Lind's two-out single, Arencibia hit the first pitch over the left field wall.
"At this level, those guys are so good it's kind of crazy," Gausman said. "I've been waiting my entire life for this. I haven't been able to sleep very much lately. That was something that was kind of great to get out of the way. Hopefully I can sleep tonight.
"My fastball felt good, my changeup felt great. I threw some good sliders. Overall I felt good throwing everything. There's was nothing I didn't really feel comfortable throwing."
NOTES: LHP Sean Nolin will make his major league debut when he starts Friday for the Blue Jays after being called up from Double-A New Hampshire. Nolin will face Orioles RHP Chris Tillman (3-2, 3.52). ... With Gausman's promotion, the Orioles optioned RHP Jake Arrieta to Triple-A Norfolk. ... Baltimore also designated for assignment RHP Alex Burnett, who was pitching for Norfolk. ... RHP Chad Jenkins will start Sunday's game for Toronto instead of RHP Ramon Ortiz. ... Gausman is the 21st pitcher used by the Orioles this season. He is the third Oriole to make his major league debut, joining LHP T.J. McFarland and RHP Zach Clark. ...Toronto RHP Josh Johnson (triceps) will make his second minor league rehab start Saturday for Triple-A Buffalo.