NEW YORK — The news about Manny Ramirez’s injury became slightly more ominous yesterday when it was revealed that the outfielder is suffering from an oblique strain, and not, as the Red Sox first said, back spasms.

Ramirez was examined yesterday by both Stuart Hershon, the Yankees team physician, and Larry Ronan, one of a team of doctors employed by the Red Sox. They found that Ramirez was suffering from a slight strain of the left oblique muscle.

Ramirez first felt soreness in the area last week, sitting out the final game of the Red Sox series in Tampa. After playing the first three games of the four-game series in Chicago, Ramirez also sat out Sunday.

He was taken out of the game after the seventh inning Tuesday night.

A club source estimated that Ramirez could miss anywhere from “days to weeks” with the injury, though the former is more likely than the latter. Ramirez told the Associated Press yesterday afternoon that he could be out of the lineup “Maybe a week.”

Oblique strains have been known to sideline players for weeks and, on rare occasions, months.

After the Red Sox’ 4-3 lost to the Yankees last night, manager Terry Francona said: “I don’t think it will be (only) a couple of days — more like multiple (days).”

Ramirez probably won’t play until next week — at the earliest.

“He’s one of our big players in the lineup,” said teammate Kevin Youkilis. “It’s definitely a concern, but we can’t worry about it.”

Ramirez is expected to be examined further tomorrow when the team returns home from its three-city road trip.

With reserve outfielder Bobby Kielty also temporarily sidelined with back spasms, stemming from a collision with the bullpen wall in Fenway two weeks ago, the Sox were short of players last night.

Eric Hinske was the starting left fielder, but the Sox had only three available outfielders last night, with shortstop Julio Lugo available in a pinch.

Rosters expand Saturday, and while the Red Sox would like to have their callups finish the International League season — which concludes Monday — the team doesn’t want to be caught shorthanded, either.

Jacoby Ellsbury will probably join the Sox on Saturday, with Brandon Moss due Tuesday.

Tavarez gets nod vs. Orioles

The Sox have changed their minds about Saturday’s starter.

The plan had been to give Clay Buchholz his second major-league start. But because Buchholz has struggled in his last two outings and, correspondingly, Julian Tavarez has sparkled in his last two spot starts, the Sox are now giving the ball to Tavarez to face Baltimore.

There was also some concern about fatigue with Buchholz. He’s pitched 125 1/3 innings at Portland and Pawtucket and another six in Boston in his major-league debut two weeks ago, easily the most he’s thrown in a single season.

Buchholz will still be added to the major-league roster when it expands and could draw another start later in the month should the Sox clinch and want to rest some of their rotation regulars.

No harm, no foul

Dustin Pedroia was hit in the top of the first by Roger Clemens. Some speculated that the plunk may have been retribution for Daisuke Matsuzaka hitting Alex Rodriguez on Tuesday night, but Pedroia didn’t think so.

“I don’t think he hit me intentionally,” said the rookie infielder. “The ball just ran on him.”

Pedroia then got caught stealing. He slid into the bag safely, but his momentum carried him past the bag, where Derek Jeter applied the tag.

Around the bases…

After winning five of the first six meetings against the Yankees this season, the Sox and Yankee season series is tied 7-7. … Mike Lowell extended his hitting streak to 11 games. He’s hit safely in 25 of 27 games in August. … Mike Timlin appeared in his 999th career game and with his next outing, can become the 13th pitcher in baseball history to make 1,000 appearances. … After last night, the Sox’ bullpen had a scoreless streak of seven straight innings and had allowed just three earned ruins in its last 28 innings. … Seen in the crowd last night: TV analyst John Madden, actors Kevin Bacon, Penny Marshall, Alec Baldwin and left-hander Paul McCartney. … With Roger Clemens (354 career wins) as the opposing starter, last night marked the 25th time since Walter Johnson retired in 1927 that the Sox had faced a 300-game winner. The last two times it’s happened, Greg Maddux was the opponent: June 10, 2005 with the Cubs and on June 22 of this year with San Diego.

smcadam@projo.com