BALTIMORE (AP) -It was a lost night for the Boston Red Sox .

First, the Red Sox lost an eighth-inning lead to the Baltimore Orioles . Then they lost the game, 6-3. Then Boston learned it lost designated hitter David Ortiz , who will be placed on the 15-day disabled list with a partially torn tendon in his left wrist.

Ortiz leads the Red Sox with 13 homers and 43 RBIs.

''He's a big part of the team,'' Manny Ramirez said Monday night after homering in a third straight game. ''We have to keep battling without David. Let's wait for him and pray that he'll get better soon.''

Ortiz received an MRI in Boston on Monday; the injury was determined to be a torn ECU tendon shead.

''Surgery is very unlikely,'' manager Terry Francona said.

The move to place Ortiz on the disabled list will occur Tuesday, Francona said, and Boston will recall right-hander Justin Masterson from Triple-A Pawtucket to fill Ortiz's spot on the roster. Masterson will start Tuesday night against Tampa Bay.

Adam Jones broke a tie with a three-run double in the eighth inning, and the Orioles overcame another home run by Ramirez to avoid a four-game sweep.

Baltimore blew a 2-0 lead, then rallied with a four-run eighth against Hideki Okajima (1-1), who came in with an 0.72 ERA. After a sacrifice fly by Kevin Millar tied it, the Orioles loaded the bases with two outs for Jones, who worked the count to 3-1 before hitting a liner off the left-field wall.

''I was just patient with him,'' Jones said. ''He threw a good pitch up and in, 2-1. I've been swinging at that pitch, but I just laid off of it.''

Jones is 3-for-5 with three doubles and nine RBIs with the bases loaded this season.

Ramirez's 12th homer of the season gave him 502 for his career, two behind Eddie Murray for 23rd place in baseball history. The sixth-inning solo shot, on an 0-2 pitch from Jeremy Guthrie , extended Ramirez's hitting streak to eight games and got Boston within 2-1.

Ramirez was the designated hitter in place of Ortiz, and will likely continue that role instead of playing left field.

''I love DH. I'm pretty sure they're not going to miss my Gold Glove out there,'' Ramirez said with a grin. ''We're fine. We're going to be fine.''

The last time Ramirez homered in three straight games was May 22-24, 2006. He also played a key role in helping Boston take the lead in the eighth, hitting a single off Jim Johnson (1-2) to put the go-ahead run in scoring position for Mike Lowell , who delivered an RBI single for a 3-2 lead.

But Ramirez flied out to right with two on in the ninth inning to end the game.

Despite the loss to Baltimore and the distressing news about Ortiz, the defending World Series champions headed back to Boston with their spirits soaring.

''The team is playing great, we take three out of four, and we're going home,'' Ramirez said.

Tim Wakefield allowed two runs and five hits in seven innings for the Red Sox , who were denied their first four-game sweep of the Orioles since Sept. 20-23, 2002.

''(Wakefield) handed the ball to the bullpen and more often than not, he gives us a chance to win when he goes out there,'' Francona said.

The Boston bullpen had gone 14 straight innings without allowing a run, and Okajima had permitted two runs all season before yielding four in two-thirds of an inning against Baltimore.

''It looked like he got a lot of fastballs over the plate. We were so comfortable getting to him,'' Francona said. ''He just threw a lot of fastballs where he didn't want to - and he still almost got out of it.''

Johnson got an inning-ending double play in the eighth to earn his first major league win, and George Sherrill got three outs for his 18th save.

Guthrie gave up two runs and eight hits in 6 1-3 innings. His lone walk, to Alex Cora , turned into the tying run when Kevin Cash followed with an RBI double to end Guthrie's outing at 120 pitches.

Guthrie is 0-3 with a 2.33 ERA in his last four starts.

Orioles manager Dave Trembley was ejected by home plate umpire Alfonso Marquez in the third inning for protesting ball and strike calls. Before leaving, Trembley took a stab at illustrating Marquez's strike zone, running his finger along the inside stripe of each batter's box.

''I yelled at him from the dugout, Those pitches aren't strikes,'' Trembley said. ''Then I had to show him where I thought they were.''

After Boston stranded two runners in the fourth, Baltimore went up 2-0 in the bottom half when Aubrey Huff hit an RBI double and scored on a single by Millar.

Notes: Boston's Coco Crisp singled in the fourth inning to snap an 0-for-23 skid. ... Cash, who usually catches knuckleballer Wakefield, leads the majors with eight passed balls - more than any other team. ... Francona returned after missing Sunday's game to attend the graduation of his daughter. Baltimore first base coach John Shelby missed Monday's game to be at his son's high school graduation. ... Boston 2B Dustin Pedroia received the night off, even though he is 5-for-9 lifetime against Guthrie.