Rapid Reaction: Orioles 2, Red Sox 1

BALTIMORE -- Even with a Roy Hobbs-like moment from Grady Sizemore, who homered for the first time in almost three years, the Red Sox are not going to go wire-to-wire in defense of their 2013 World Series title.

The result: The Baltimore Orioles beat the Red Sox 2-1 on a tiebreaking home run by Nelson Cruz, who did not sign with the Orioles as a free agent until after the start of spring training. Cruz, who is batting .459 lifetime (11-for-24) against Jon Lester, hit the left-hander’s first pitch in the seventh inning to break a 1-1 tie before a sellout crowd of 46,685 at Camden Yards.

Hunter holds on: Tommy Hunter, who is replacing Jim Johnson as the Orioles' closer, hit Will Middlebrooks with a pitch and gave up a two-strike single to Dustin Pedroia with one out, but retired David Ortiz on a fly ball to left and struck out rookie Jackie Bradley Jr., who had entered the game as a pinch runner for Mike Napoli in the eighth.

The crux of the matter: The Red Sox left 12 men on base, including five in the first three innings and two in the ninth, and were 0-for-10 with runners in scoring position.

Sizemore shines: Sizemore singled in his first at-bat in the second inning, his first hit in 921 days (previous hit: Sept. 22, 2011). He then homered to lead off the fourth against Orioles right-hander Chris Tillman, the ball hitting the top of the video board in right.

Lester takes the loss: Lester, making his fourth straight Opening Day start, was sharp, allowing just six hits and two earned runs while walking one and striking out eight.

Missing in action: Shane Victorino went on the DL before the game with a strained right hamstring.

Baltimore blues: The Sox have not won an opener in Baltimore since a 2-0 win in Memorial Stadium in 1982.