BALTIMORE — Left fielder Nelson Cruz made quite a debut with the Baltimore Orioles on opening day against the Boston Red Sox.

Cruz homered on the first pitch in the bottom of the seventh to give the Orioles a 2-1 victory over World Series champion Boston on Monday afternoon.

Cruz led off the seventh by sending a Jon Lester fastball into the left-field seats, snapping a 1-1 tie. Lester kept the Orioles quiet before that, retiring nine of the previous 10 batters he faced before Cruz got the tie-breaking hit in his first game as an Oriole.

“I tried to dream about a good start,” Cruz said. “I think the dream (came) true.”

Cruz joined the Orioles as a free agent late in the offseason. He finished the day 1-for-2 with a walk, scored both Baltimore runs and made a big catch in left field earlier in the game.

That nice catch Cruz made got the sellout crowd of 46,685 chanting “Cruuuuuz” throughout the afternoon whenever he was involved in a play. It wasn’t a playoff game, but there was plenty of noise at Camden Yards during the game.

“Obviously, you play the game with emotion,” Orioles manager Buck Showalter said. “It’s kind of like spring training and the first day of the season, there are certain parts that people grow up with, and it’s the start of something. A lot of emotion there.”

The crowd also roared when pitcher Tommy Hunter made his debut as the Orioles closer and retired the Red Sox in the ninth. Hunter’s strikeout of right fielder Jackie Bradley Jr. to end the game got the crowd fired up.

“Hopefully it’s like that a lot more,” Hunter said. “That was enjoyable. That’s the way of life in baseball, I think. You’ve got to earn everything you get. One-run game to start the season off against the defending world champs, here we are.”

The Orioles didn’t have nearly as many offensive chances as Boston did, but the Red Sox couldn’t take advantage of those opportunities. Boston finished 0-for-10 with runners in scoring position and left 12 on base.

Baltimore left only three on base and went just 0-for-1 with runners in scoring position.

The lack of timely hitting proved costly to Lester, who threw seven solid innings. He gave up two runs on six hits and posted eight strikeouts with just one walk.

“I thought Jon Lester was in control of the ballgame here today,” Red Sox manager John Farrell said. “(The Orioles) made the most of the hits they put up.”

Zach Britton (1-0) got the win thanks to two innings of scoreless relief for starter Chris Tillman. Britton blanked the Red Sox in the sixth and seventh.

Evan Meek then replaced Britton and got the first two outs in the eighth. Brian Matusz came on for Baltimore with two on and two outs to finish the inning by getting catcher A.J. Pierzynski to ground out. Hunter then finished it in the ninth.

The Orioles had taken a 1-0 lead in the second, again with help from Cruz. He drew a leadoff walk and went to third when catcher Matt Wieters followed with a single. Cruz then scored on designated hitter Delmon Young’s double-play grounder.

Boston tied it when center fielder Grady Sizemore led off the fourth with a solo homer that just made it on top of the right-field scoreboard off Tillman. He gave up one run on seven hits in five innings, escaping jams three times as the Red Sox repeatedly worked the count.

Tillman threw 104 pitches in five innings despite walking just one batter. Boston left runners at third three times in the first six innings and missed several scoring opportunities.

“We got a lot of guys on,” said Boston second baseman Dustin Pedroia. “A lot of guys hit the ball right at people. It was just one of those deals where we couldn’t find a way to push the runs across.”

NOTES: The Orioles gave Gold Gloves to center fielder Adam Jones, shortstop J.J. Hardy and third baseman Manny Machado, who also got a Platinum Glove before the game. … The crowd of 46,685 was the 23rd straight sellout on opening day at Oriole Park at Camden Yards. … The Red Sox placed right fielder Shane Victorino on the 15-day disabled list — retroactive to Sunday — due to a strained hamstring he suffered this weekend. They recalled outfielder Jackie Bradley Jr. from Triple-A Pawtucket to replace Victorino. …Sizemore had missed all of the last two seasons with injuries, and his home run was his first since July 15, 2011 — also against the Orioles in Baltimore.