MLB

JOBA’S SHOULDER BEARS WATCHING

For the second time inside of two months, Joba Chamberlain experienced discomfort in his valuable right shoulder Sunday at Fenway Park.

According to several people, Chamberlain said the shoulder was tight after exiting the first game of the doubleheader against the Red Sox when he walked Jason Bay and gave up a ground-rule double to Mark Kotsay in the eighth inning.

The same people said Chamberlain didn’t appear too concerned about it. However, Chamberlain is the face of the Yankees’ pitching future and the slightest physical problem with him is cause for concern. Especially with the Yankees targeting starting pitching as the No. 1 area they have to upgrade this winter.

Chamberlain, 23, was brought in to protect a three-run lead in Mike Mussina’s quest for a 20th win and was hooked after two batters. He was relieved by Brian Bruney, who, with Mariano Rivera, helped Mussina win 20 games for the first time.

According to a scout who recently tracked Chamberlain, tightness could be why his velocity was down during the final two weeks of the season.

“He was throwing 91 mph and a lot of sliders,” the scout said of Chamberlain, whose fastball was clocked at 97-98 mph before he spent almost a month on the DL with rotator-cuff tendinitis.

Sunday, while fielding questions about where Chamberlain will be used next year – starter or reliever – Joe Girardi said he believed the club could keep Chamberlain healthy no matter what role.

Chamberlain, who opened the year in the bullpen and began a conversion process on May 21 that resulted in his first start on June 3, left an Aug. 4 game in Texas during the fifth inning. He underwent an MRI the next day and was examined by noted orthopedic surgeon Dr. James Andrews in Florida.

Andrews diagnosed Chamberlain with rotator-cuff tendinitis and he was out until Sept. 2 when he returned as a reliever.

In a dozen starts Chamberlain was 3-1 with a 2.76 ERA. As a reliever he was 1-2 with a 2.38 ERA in 30 appearances after being charged with two runs Sunday. Since coming off the shelf he has a 2.38 ERA in 10 games.

In August, Chamberlain was frightened because he never experienced a shoulder problem and was relieved to be without structural damage.

Early in his return from the DL, Chamberlain complained about his mechanics being off. However, he fanned 14 in 10 innings and gave up one run until Sunday.

Chamberlain said he was open to whatever the Yankees wanted him to do next year. That likely will depend on what their rotation looks like going into spring training.

They are prepared to throw sick money at CC Sabathia to get the free-agent lefty and might be willing to chase A.J. Burnett if Sabathia turns them down.

If they land one of those hurlers, sign a lesser free agent like Derek Lowe and bring back Chien-Ming Wang to join Andy Pettitte, who is likely to return, it’s possible Chamberlain could start the season in the bullpen again.

However, if Sabathia and Burnett don’t come, Chamberlain will be needed in a questionable rotation.

george.king@nypost.com