NEW YORK -- It's hard to know what to expect from A.J. Burnett come the playoffs.
Will it be the dominant pitcher who went 5-0 with a 2.01 ERA from June 27 to July 27? Or will it be the struggling starter who is 1-5 with a 6.19 ERA since?
Brian Roberts hit a grand slam in a six-run second inning and tied a franchise record with his 51st double. That backed rookie Brian Matusz (5-2), who allowed one run and four hits in seven innings to win his third straight start.
New York lost consecutive games for the first time since Aug. 16-17 at Seattle and Oakland -- and dropped back-to-back games at home for the first time since June 17-18 against Washington.
A day after surpassing Lou Gehrig for the Yankees career hits lead, Derek Jeter received more standing ovations and went 1 for 5 to leave his total at 2,724. But back on the field less than 12 hours following the end of Friday night's rain-delayed 10-4 loss, New York (91-52) was flat.
"We have not clinched anything or won anything yet," Jeter said. "Our focus has always remained to try to win games and win the division, so that's what everyone's looking forward to."
Burnett (11-9) allowed six runs and seven hits in seven innings. Staked to a lead by Mark Teixeira's first-inning sacrifice fly, he gave up Nolan Reimold's leadoff homer in the second -- Baltimore's first home run in 42 2/3 innings since Reimold connected off Texas' Kevin Millwood on Sept. 5.
A walk and three singles put the Orioles ahead, with Robert Andino driving in the go-ahead run, and Roberts homered on a slider left over the plate. It was the third slam at new Yankee Stadium -- all by visitors.
"It was a bit of surprise to have that big an inning," said Roberts, who went 3 for 4 and finished a triple shy of the cycle.
Burnett appeared far from ready to follow CC Sabathia and start Game 2 or 3 of the postseason next month. He has allowed a career-high 24 homers, yet doesn't think he's been that far off.
"I left one over, you know, a little too much at the wrong time," he said. "It's been one mistake here or there."
While Burnett retired 17 of 19 batters after the slam, three of the first five outs during that stretch were flies to the warning track. Catcher Jose Molina said Burnett might be tired at this point of the long season.
"That's a question a lot of people have got to ask," he said. "I don't think he's tired. I don't think he needs a rest. I think he's 100 percent ready to go because to me he seems like he's battling every time."
Matusz, a 22-year-old left-hander, was making his eighth career start and first against the Yankees.
"I thought it was the best start of the year. The atmosphere, that was really cool, with the first guy I'm facing being Jeter, but I was able to relax," he said. "I felt it a little bit. It's every kid's dream to pitch at Yankee Stadium."
Matusz impressed a team that leads the major leagues with 816 runs.
"He was moving the ball in and out. He was mixing his breaking balls, changeup," Jeter said. "He was never really in trouble."
While the Orioles are last in the AL East at 58-83, outings by Matusz and 21-year-old rookie Chris Tillman on Friday gave them a lift.
"It makes you feel good heading into the last few weeks of the season about what the future possibly holds," manager Dave Trembley said.
Roberts has five slams. He also hit one Aug. 20 off Lance Cormier at Tampa Bay. ... Cleveland's Grady Sizemore and Asdrubal Cabrera hit slams in the first series at the ballpark. ... Roberts also hit 51 doubles last year and shares the franchise record with Baby Doll Jacobson (1926 St. Louis Browns) and Beau Bell (1937 Browns). ... Yankees LF Johnny Damon missed his second straight game because of a stiff back and hamstrings. Yankees manager Joe Girardi said Damon likely will start Sunday. ... Removal of the facade in the outfield at old Yankee Stadium began last week.