BOSTON — Josh Beckett celebrated his 27th birthday yesterday by throwing a bullpen session.

But the right-hander, who had to leave his start Sunday because he tore skin on his right middle finger while throwing a curveball, still is no lock to make his next scheduled start on Friday night against Atlanta.

In fact, it’s more likely that he won’t make the start even though Beckett, manager Terry Francona and pitching coach John Farrell were encouraged just by the fact that he was able to throw off the mound so soon after suffering the avulsion.

Yesterday was Beckett’s normal between-starts throwing day. Beckett, who had a bandage on the tip of his middle finger, began yesterday’s workout by playing long toss from about 150 feet. He felt good doing that, so he went into the bullpen.

It wasn’t a normal bullpen session. Beckett, who is 7-0, threw only fastballs and changeups — no curveballs, which would have put undue pressure on the damaged area of his finger — and didn’t have much snap on those pitches.

“It wasn’t an all-out bullpen session in terms of intensity and duration,” Farrell said. “We have to use caution and not rush him back and jeopardize a larger down time. Not knowing how long he’ll be out, we want to manage it (the injury) and keep his arm in shape so he’ll be able to pitch effectively when he does come back.”

Farrell said the Sox were not likely to bring him back if he “were any less equipped” in his arsenal of pitches, meaning unable to snap off his curveball without confidence and comfort.

“It was very encouraging how good he felt, how much this thing seemed to be regenerating quickly,” said Francona. “Regardless of whether he pitches on Friday, the news is good.”

Beckett was expected to see a hand specialist last night. If Beckett can’t pitch Friday, Kyle Snyder could be the likely candidate to fill his spot in the rotation.

Timlin on the mend

Beckett wasn’t the only pitcher working off positive news. Doctors determined that Mike Timlin’s tendinitis was progressing enough for him to begin a throwing program. The plan is for the veteran reliever to ‘flat ground catch’ up to 90 feet yesterday and today, take a day off on Thursday and then repeat the same throwing for the following two days.

“It’s all according to how he’s progressing,” said Francona.

Drew injured

Outfielder J.D. Drew had to leave the game last night after suffering a lower back contusion.

Drew was chasing a home run by Brandon Inge in the third inning and slammed awkwardly into the wall in front of the Boston bullpen. There is no padding where Drew’s body met the wall.

He remained in the game for his next two at-bats, but was replaced by Eric Hinske in the top of the eighth.

“His back is a little sore,” Francona said. “He went up and hit the top of the wall with the base of his back, the part (of the wall) that’s not padded. I think he hit his elbow, too. His lower back got tight, and tighter as the game progressed. We’d much rather be safe than sorry.”

Francona said Drew will be evaluated today, though with a left-handed pitcher (Mike Maroth) scheduled to start tonight for Detroit, it might be a good time to give Drew the night off and give Wily Mo Pena some at-bats.

Drew has been struggling at the plate over the last couple of weeks, but it was his low liner to left field in the bottom of the first that scored Kevin Youkilis and put Boston up, 1-0.

Mirabelli on upswing

Doug Mirabelli played in his 11th game of the season last night and the eighth catching Tim Wakefield. After slumping noticeably at the end of last season, he came into last night hitting .280 with 2 homers and 4 RBI. The Red Sox chose to resign Mirabelli in the off-season, principally to secure the catching duties for Wakefield’s fluttering knuckleball. But the team certainly hoped for better production (.193 average in 59 games) than what the veteran delivered last year.

“Sometimes you get to a point in your career where you have to work harder than you did before to maintain where you were,” said Francona. “Players, you hope, understand that. And it looks like he did.”

Francona said that Mirabelli’s hands seem quicker and he’s getting the head of the bat into the strike zone more often.

“He’s strong enough and has good enough hands where if he gets the head of the bat (on the ball), especially in this ballpark, he can do some damage,” said Francona. “He’s gotten back to that but if you get away from that you can’t (always) find it. I think he’s worked hard to get himself in better shape and it’s easier for him to get the head of the bat to the ball.”

Around the bases

Keith Lockhart of the Boston Pops Orchestra threw out the first ball. … Diasuke Matsuzaka’s complete game win Monday night was the first complete game by a Red Sox starter since Wakefield did it last April against Seattle. He’s the first Red Sox rookie to hurl a complete game since Tim VanEgmond in 1994. Wakefield leads all current Red Sox pitchers with 29 complete games.

smanza@projo.com