Minus their star catcher, the New York Yankees waited at home plate in a merry pack of pinstripes as Nick Swisher circled the bases following his game-winning home run.

Jorge Posada was missing — but he could be back soon.

Swisher hit a two-run homer off Koji Uehara in the bottom of the ninth inning Wednesday to give New York a 3-2 victory over the Baltimore Orioles that was soon tempered by news of Posada's aching head.

Following the game, Yankees manager Joe Girardi revealed that Posada felt concussion symptoms Tuesday night after getting hit by a foul ball. The switch-hitting slugger sat out Wednesday and was sent to New York-Presbyterian Hospital during the game to see a neurology specialist.

"Obviously, it's a concern," Swisher said.

A little while later, the Yankees announced tests came back negative and Posada was cleared to play. He is day to day and is expected to travel with the team on its upcoming road trip.

"He's a big part of our ballclub and hopefully he'll be back in the lineup in a couple of days," Yankees outfielder Brett Gardner said before the results were announced.

Losing Posada would be a major blow to the AL East leaders, trying to repeat as World Series champions. Several big league stars have been sidelined by concussions for extended stretches this season, including Minnesota slugger Justin Morneau and New York Mets outfielder Jason Bay.

With the Orioles closing in on their first three-game sweep in the Bronx since 1986, Alex Rodriguez opened the ninth with a single on the first pitch from Uehara (1-1). Robinson Cano flied out and Swisher, hobbled by a stiff left knee, drove a 2-0 pitch to the opposite field and into the Baltimore bullpen in left-center.

It was Swisher's 26th home run of the season and his third career game-ending shot. The previous one came exactly a year before, against Tampa Bay's Dan Wheeler.

"I guess it's my day," Swisher said. "It's a monster win for us."

Swisher began the day in an 0-for-14 slide before getting two hits. He raised his arms as he rounded first base in the ninth and tossed his helmet high in the air as he approached a mob of jubilant teammates waiting for him at home plate.

Moments later, Swisher took the familiar whipped cream pie in the face from pitcher A.J. Burnett.

"Was the whipped cream fresh? They hadn't done it in a while," Girardi said.

Matt Wieters hit a two-run homer and Brad Bergesen pitched 6 1-3 impressive innings for Baltimore.

The resurgent Orioles, with the worst record in the AL but gaining fast on Seattle, fell just short of their first five-game winning streak since June 2009. They are 21-14 under Buck Showalter, who managed the Yankees from 1992-95.

"I'm proud of our guys. This one stings a bit right now, but you can't think of what could've been," Showalter said.

New York got a solid start from rookie Ivan Nova and ended a three-game skid that followed a season-best eight-game winning streak. The Yankees are the only team in the majors without a four-game losing streak this year.

New York has never been on the wrong end of a three-game sweep in its new stadium, which opened last season. The only time the Yankees were swept this year was in a two-game series May 19-20 against Tampa Bay.

"That was the one thing I didn't want to give up — a home run," Uehara said through a translator. "I'm not feeling good about it."

Joba Chamberlain (3-4) struck out two in a hitless ninth. Slumping shortstop Derek Jeter went 0 for 4 with a throwing error, dropping his batting average to .262.

Playing before an unusually sparse crowd, the Yankees finished 7-3 on their longest homestand of the season. They were 4-3 during a seven-game stretch that included six day games.

New York has 22 games remaining, 15 on the road.

With the Orioles trailing 1-0, Adam Jones beat out an infield single to open the fifth. Turned loose on 3-0, Wieters hit an opposite-field drive that sailed wind-aided deep into the left-field stands.

Bergesen held the Yankees to three hits through six innings. Curtis Granderson drew a leadoff walk in the third and stole second base. He scored from third on a one-out double to left by Gardner, who was cut down trying to stretch it into a triple. Felix Pie started a crisp relay.

NOTES: Girardi said he foresees a platoon of Lance Berkman and Marcus Thames at designated hitter the rest of the way. Berkman played first base Wednesday, with Mark Teixeira getting a semi-rest as the DH. ... Thames hit New York's other game-ending homer this season, May 17 against Boston. ... The Yankees have won 12 of 16 at home. ... Baltimore wound up two outs shy of winning six consecutive road games for the first time since 2004.