BALTIMORE (AP) — Grady Sizemore will never forget his first opening day with the Boston Red Sox.

His teammates, however, can’t wait to put the memory of the game behind them.

The defending World Series champion Red Sox failed to capitalize on several scoring opportunities, and a home run by Sizemore wasn’t enough to prevent a 2-1 loss to the Baltimore Orioles on Monday.

After missing two seasons recovering from knee surgery, Sizemore marked his return from a 922-day absence with a second-inning single for his first hit since September 2011. The three-time All-Star for Cleveland later hit his first homer since July 15, 2011, which also came at Camden Yards.

“Today was very exciting,” Sizemore said. “I couldn’t wait to get to the ballpark.”

The single was particularly gratifying, because it came on his first at-bat.

“Having gone through what I’ve gone through, it was nice to get that moment,” Sizemore said.

His homer created a 1-1 tie in the fourth inning, but that would be the extent of the Boston offense. The Red Sox got nine hits and drew three walks, but they stranded 12 and went 0 for 10 with runners in scoring position.

“There were a lot of opportunities that we did create but didn’t cash in,” manager John Farrell said. “The two-out hit was elusive.”

Second baseman Dustin Pedroia, who went 2 for 5, added, “We just hit the ball right at people. It was one of those deals where we couldn’t find a way to push runs across.”

Nelson Cruz homered off Jon Lester (0-1) in the seventh inning to put the Orioles up 2-1. Cruz hit 27 homers last year with Texas during a season marred by a 50-game suspension from Major League Baseball in the Biogenesis drug scandal.

“It was really neat, it was special,” he said. “I made the right call to come and be part of this organization, be part of this town.”

Zach Britton (1-0) got the win with two scoreless innings of relief and Tommy Hunter got three outs for the save. Hunter earned the job as closer this spring after the Orioles dealt away Jim Johnson during the offseason.

The Red Sox got two on with one out in the ninth before World Series MVP David Ortiz hit a flyball and Jackie Bradley Jr. took a called third strike.

Making his fourth straight opening day start for Boston, Lester gave up two runs, six hits and a walk in seven innings. He struck out eight.

“It was good. Obviously, the only thing better would be if we win,” the left-hander said. “Other than that I thought I threw the ball well.”

Orioles starter Chris Tillman allowed one run, seven hits and a walk in five innings. The right-hander went 3-1 against Boston last year, but in this one he needed 104 pitches to get 15 outs.

Britton gave up a one-out double to Xander Bogaerts in the sixth and got three straight outs in the seventh, the only time all day that Boston went down in order.

Evan Meek walked two in the eighth before Brian Matusz retired A.J. Pierzynski on a comebacker.

Gametime temperature was announced at 60 degrees, but a stiff wind chilled many in the crowd of 46,685 — the 23rd consecutive opening day sellout at Camden Yards.

Hopeful that the offseason acquisitions of Cruz and right-hander Ubaldo Jimenez will enable Baltimore to return to the playoffs after missing out last year, Orioles fans were out in force. Until recently, games against Boston often drew as many Red Sox backers as those rooting for the home team.

“Our crowd was legit,” Hunter said. “That was awesome. I hope they come out like that every game for 80 more here.”

The Orioles used a walk, a single by Matt Wieters and a double-play grounder to take a 1-0 lead in the second.

The Red Sox put runners at second and third with two outs in the third before Tillman struck out Mike Carp. In the fourth, Sizemore hit a 3-1 pitch over the right field wall.

NOTES: Pedroia got Boston’s first hit of the season, a one-out single in the first inning, to extend his hitting streak on opening day to eight games. … After taking Tuesday off, the teams meet Wednesday night. John Lackey (13-5 lifetime against Baltimore) faces Jimenez in his Orioles debut. … The Red Sox put RF Shane Victorino (hamstring) on the 15-day disabled list and recalled Bradley. … Ortiz received his 12th opening day start at DH, tying Don Baylor’s major league record at the position.