The euphoria from a three-game sweep of the Orioles Wednesday quickly gave way to uncertainty and concern once Andy Pettitte's MRI results became known after the game.

The 37-year-old lefthander has mild inflammation of the left elbow. He was removed after pitching five innings in a 7-5 victory at the Stadium and taken to Columbia Presbyterian Hospital for tests. His injury will be treated "conservatively" and he'll be evaluated on a "daily basis," the team said.

General manager Brian Cashman said he was relieved there was no structural damage to the elbow. "It's safe to believe he'll miss a start, but that's just my thought, and we haven't been able to sit down and talk about it," he said.

Cashman added that he didn't see the disabled list as an option right now.

Pettitte had elbow surgery in 2004. "Anytime you are talking about the area around the elbow, you start to worry a little bit," he said through a team spokesman before learning the MRI results.

He had thrown only 77 pitches (46 for strikes) when Joe Girardi pulled him after the fifth.

"He felt a little stiffness right here on the top of his arm against the White Sox [Friday]," the manager said. "So he came in after his bullpen, [he was] getting loose, the trainer rubbed it out. He felt nothing during [Friday's] game. We backed him off his bullpen a little bit.

"Today he felt a little stiffness again warming up, talked to the trainer, rubbed it out, checked with him after the first, the second, the third, the fourth. In those innings, he said he felt fine. In the fifth, he said, 'You know what' - and I had to drag it out of him - 'I feel a little stiff.' He wanted to stay in the game."

Pettitte (4-0, 2.08 ERA) looked shaky in spots but gave up only one earned run, six hits and two walks. His only hiccup came in the fourth, when he allowed back-to-back singles to Nick Markakis and Miguel Tejada before walking Garrett Atkins and Nolan Reimold to force in a run. Pettitte improved to 27-6 against the Orioles, his most wins against any franchise.

Pitching coach Dave Eiland said he saw nothing out of the ordinary with Pettitte's mechanics or command. "Not at all," he said. "If we saw something that would've raised eyebrows, we would have gotten him out right then and there . . . He probably could have stayed in the game but we didn't let him."

A rash of injuries have sidelined closer Mariano Rivera (left side stiffness), Jorge Posada (mild calf strain) and Curtis Granderson (groin strain). The Yankees, who have won seven of eight, hope they can ride the momentum into a weekend series in Boston.

Nick Johnson (3-for-3) crushed a homer off David Hernandez (0-4) in the first and raised his average 37 points to .171. Nick Swisher also hit a solo shot in the second, and Mark Teixeira (.178) drove in two runs with a double in the fourth.

The Orioles pulled to within 6-3 on a two-run homer by Ty Wigginton off Sergio Mitre in the eighth, and Matt Wieters and Reimold drilled back-to-back homers off David Robertson with one out in the ninth. Boone Logan then sandwiched two walks around a flyout. With Joba Chamberlain and Rivera unavailable, Alfredo Aceves got the last out with the tying runs on base.

With Jim Baumbach

More Yankees headlines