By Steve Keating

TORONTO (Reuters) - Few pitchers have been handed a better opportunity to notch their first Major league win than Brad Mills and he did not waste it, delivering a masterful two-hit effort in the Toronto Blue Jays' 5-0 victory over the Baltimore Orioles on Wednesday.

Summoned from Class AAA Las Vegas to make an emergency start, Mills delivered seven masterful innings, allowing just two singles before turning the ball over to the bullpen to complete a three-hit shutout.

Twice knocked around by the World Series champion Philadelphia Phillies in a miserable big league stint a year ago, Mills had the good fortune of facing the worst team in the major leagues in his third career start.

Backed by baseball's most explosive offense that has slammed 155 home runs, Mills delivered a cool performance on a muggy evening, striking out four and walking three as Toronto remained unbeaten against the Orioles in 12 meetings this season.

"I'll take it," a beaming Mills told reporters. "I just tried to throw as many strikes as I could. I just tried to keep it as simple as possible.

"Last year didn't go the way I wanted to so it's great to come up here and prove to myself that I belong here, I can pitch here.

"Regardless if I'm staying or going down I know I can pitch here."

The Blue Jays have outscored Baltimore 70-23 this season and slammed 24 homers while the Orioles have answered with four.

But the Jays' big bats did not provide the type of early support Mills might have hoped for, forcing the 25-year-old left-hander to nurse a 1-0 lead to the eighth inning.

Lyle Overbay ended the suspense with a three-run blast to key a four-run eighth and help send the Orioles to their 70th loss.

Baltimore's first batter, Brian Roberts, welcomed Mills back to the big leagues with a hard single to left but that would be the last hit he would surrender until a two-out single in the seventh.

Mills's sparkling display earned a standing ovation from the small crowd but it was not enough to keep him in Toronto, the rookie packing his bags immediately after the game for a return trip to the minors.

"He didn't scare out there at all," said Blue Jays manager Cito Gaston. "This game you never know what you might see and tonight you saw a kid go out and pitch a two-hitter and you also saw a kid I had to send back down to Triple A.

"That was kind of tough but as I told him, if we need a starter somewhere down the line we know where to go get him."

(Editing by Steve Ginsburg)